Lib. 


v       '.  V.A 

-~~*- 


TO  THE  MEMORY 

of 
MY  FATHER 

This  Volume  is  Dedicated 


COPYRIGHT,     191S 
O.  F.  HUNZIKER 


CONDENSED  MILK  and  MILK  POWDER 


SECOND    ED  ITION 

AND  ENLARGED 


PREPARED  FOR  THE  USE  OF 

Milk  Condenseries,    Dairy  Students   and 
Pure  Food  Departments 


By 

OTTO  F.  HUNZIKER,  B.  S.  A.,  M.  S.  A. 

\  \ 

Formerly  Professor  of  Dairy  Husbandry,  Purdue  University 
and 

Chief  of  the  Dairy  Department  of  the 

Indiana  Agricultural  Experiment  Station 

LaFayette,  Indiana 

Now  Manager  Manufacturing  Department  and  Director  Research  Laboratory 

Blue  Valley  Creamery  Co. 

Chicago 


Published    by    the    Author 
La  Grange.    Illinois 

1918 


I     L    <"? 

H 


.  DEPT, 


PREFACE 


This  book  treats  of  the  various  phases  of  the  condensed  milk 
and  powdered  milk  industry.  It  discusses  every  step  in  the 
process  of  manufacture,  following  the  milk  from  the  farmer's  door 
to  the  finished  product  in  the  pantry  of  the  consumer.  The  processes 
of  condensing  and  desiccating  milk,  skim  milk,  buttermilk  and  whey 
are  given  special  attention  and  the  defects  of  the  product,  their 
causes  and  prevention  are  explained  in  detail. 

The  inception  of  this  publication  is  the  result  of  innumerable 
and  persistent  calls  for  definite  and  reliable  information  on  the  sub- 
ject of  condensed  milk  and  milk  powder,  from  manufacturers  in  this 
country  and  in  foreign  lands ;  from  parties  contemplating  embarking 
in  the  business ;  from  national  and  state  experiment  stations  which 
are  oftentimes  called  upon  to  investigate  condensed  milk  defects; 
from  dairy  schools  desiring  to  give  instruction  on  the  subject ;  from 
national  and  state  pure  food,  departments,  seeking  information  con- 
cerning the  possibilities  and  limitations  of  manufacture,  in  their 
efforts  to  formulate  and  enforce  standards  and  laws ;  and  from  com- 
mercial chemists  in  need  of  reliable  methods  of  analyses  of  these 
special  dairy  products. 

The  information  contained  in  this  volume  represents  the 
author's  experience,  covering  a  period  of  twelve  years,  in  the  prac- 
tical manufacture  of  condensed  milk,  as  expert  advisor  to  milk 
condensing  concerns  in  the  United  States,  Canada  and  Australia, 
and  as  visitor  of  condensed  milk  and  milk  powder  factories  in  this 
country  and  in  Europe. 

It  is  the  author's  hope  that  the  information  contained  herein 
may  serve  as  a  guide  to  manufacturers,  investigators,  teachers  and 
food  authorities,  alike ;  that  it  may  assist  in  a  better  understanding 
and  wider  dissemination  of  the  principles,  phenomena  and  facts 
involved  in  the  processes  of  manufacture;  and  that  it  may  lift  the 
obstructing  veil  of  unnecessary  secrecy  which  has  hovered  over 
these  industries  since  their  beginning,  curtailing  their  development 


and  depriving  them  of  much  of  the  light  of  advanced  science  to 
which  they  are  justly  entitled  and  which  they  need  for  their  greatest 
development  for  the  lasting  benefit  of  the  producer,  manufacturer 
and  consumer  alike. 

O.  F.   HUNZIKER. 
Purdue  University,  March,  1914. 

PREFACE  FOR  SECOND  EDITION 

Since  the  issuance  of  the  First  Edition  of  this  treatise  many 
changes  have  taken  place  in  the  various  phases  of  the  Condensed 
Milk  Industry.  Old  processes  have  been  modified  and  improved, 
new  processes  have  been  invented,  the  equipment  used  for  manu- 
facture has  undergone  changes,  new  tests  have  been  devised  for  the 
determination  of  the  composition  of  the  finished  products  and  the 
entire  status  of  the  industry  has  yielded  to  an  unexpected,  unfore- 
seen and  important  evolution. 

Of  the  most  outstanding  new  features  in  this  edition  may  be 
mentioned  the  chapters  on  the  Continuous  Concentrator,  the  Stand- 
ardization of  Condensed  Milk  and  Milk  Powder,  Malted  Milk,  the 
Mojonnier  Test,  Bacteriological  Analyses.  Important  additions 
have  also  been  made  to  the  chapters  on  History  of  the  Industry, 
Volume  of  Output,  Markets,  Exports,  Imports,  Cost  of  Manufac- 
ture and  the  various  processes  of  manufacture  of  Condensed  Milk, 
Condensed  Buttermilk  and  Milk  Powder. 

In  preparing  the  Second  Edition,  the  author  has  endeavored 
to  completely  revise  the  old  edition,  incorporating  in  the  revised 
edition  the  many  changes  which  the  tooth  of  time  has  wrought  and 
to  bring  this  treatise  in  all  its  important  phases  up-to-date. 

O.    F.    HUNZIKEX 
Chicago,  111.,  July,  1918. 


CONTENTS 


PART  I 
CONDENSED  MILK 

Chapter  I 

Definition 

History  and  Development  of  Industry — Invention  of  process;  develop- 
ment of  industry;  output  of  condensed  milk  in  the  United  States; 
1899  to  1917 Pages  17-27 

Chapter  II 

Essentials  of  Suitable  Locations  for  Milk  Condensing  Factories — Milk 
supply;  water  supply;  transportation  facilities;  other  conditions. 

Building  and  Equipment — Material  of  construction;  drainage;  general 
plan  of  factory;  list  of  equipment;  economic  arrangement  of 
machinery;  sanitary  arrangement  of  machinery Pages  28-41 

Chapter  III 

Milk  Supply — Basis  of  buying  milk;  quality;  control  of  quality;  in- 
spection of  milk  at  the  condensery;  tests  for  purity  of  milk. 

Factory  Sanitation — Effect  on  patrons;  effect  on  wholesomeness  of 
product;  effect  on  marketable  property  of  product;  how  to  keep 
factory  in  sanitary  condition;  care  of  milk  in  factory  prior  to 
manufacture  Pages  41-53 


PART  II 
MANUFACTURE    OF   SWEETENED    CONDENSED   MILK 

Chapter  IV 
Definition 

Heating — Purpose;   temperature;   manner;   advantages   and  disadvan- 
tages of  different  methods. 
Addition  of  Sugar — Kinds;  quality;  amount;  mixing  the  sugar. 

Pages  54-62 
Chapter  V 

Condensing — Description  of  the  vacuum  pan. 

The  Condenser — Surface  condenser;  barometric  condenser;  wet- 
vacuum  spray  condenser;  care  of  the  condenser. 

The  Expansion  Tank,  Catch-All,  or  Milk  Trap. 

The  Vacuum  Pump. 

Science  and  Practice  of  Condensing  in  Vacuo — Object;  relation  of 
pressure  to  boiling  point;  relation  of  altitude  to  atmospheric 
pressure;  relation  of  steam  pressure  in  jacket  and  coils,  water 
in  condenser,  temperature  in  pan,  and  vacuum,  to  rapidity  of 
evaporation. 

Starting  the  Pan. 

Operating  the  Pan. 

Prevention  of  Accidents Pages  62-87 


X  CoNDl^NvSED    MlLK   AND    MlI^K    POWDER 

Chapter  VI 

Striking  or  Finishing  the  Batch — Definition;  ratio  of  concentration; 
methods  of  striking. 

Use  of  the  Beaume  hydrometer;  correction  of  Beaume  reading  for 
temperature   variations;   specific   gravity   of   sweetened   con- 
densed milk  of  different  Beaume  degrees;  sampling  the  batch. 
Drawing  off  the  condensed  milk. 
Cooling  the  Condensed  Milk Pages  87-97 

Chapter  VII 

Filling — Filling  in  barrels;  filling  in  cans. 

Sealing — Kinds   of  seals;   soldering  devices   and   machinery;   solder; 
soldering  flux;  gas  supply,  gas  generators Pages  97-103 


PART  III 

MANUFACTURE  OF  UNSWEETENED   CONDENSED  MILK 
EVAPORATED  MILK 

Chapter  VIII 

Definition. 

Quality  of  Fresh  Milk. 

Heating  the  Milk. 

Condensing. 

Striking — Use  of  the  Beaume  hydrometer;  correction  of  Beaume  read- 
ing at  temperatures  other  than  60°  F.;  calculation  of  specific 
gravity  from  Beaume  reading 104-110 

Chapter  IX 

Homogenizing — Purpose;  principle  of  the  homogenizer;  kinds  of 
homogenizers;  operation  of  the  homogenizer;  effect  on  casein. 

Pages  110-114 
Chapter  X 
Cooling. 

Filling,  Filling  Machines. 
Sealing,  Sealing  Machines Pages  114-120 

Chapter  XI 

Sterilizing — Purpose  of  sterilization;  sterilizers;  loading  the  sterilizer; 
uniform  distribution  of  heat;  temperature  and  time  of  exposure; 
qualifications  of  processor;  rapid  and  uniform  cooling;  fractional 
sterilization. 

Shaking — Methods  of  shaking;  speed  of  the  shaker;  efficiency  of  dif- 
ferent types  of  shakers;  formation  of  curd  not  desirable  nor 
necessary. 

Incubating Pages  120-129 

Chapter  XII 

Plain  Condensed  Bulk  Milk — Definition;  quality  of  fresh  milk;  heating 
of  fresh  milk;  condensing;  superheating;  striking;  ratio  of  con- 
centration; cooling  Pages  129-132 


CONDENSED  MILK  AND  MILK  POWDER  XI 

Chapter  XIII 

Concentrated  Milk — Definition;  apparatus  needed;  operation  of  Camp- 
bell process;  advantages  and  disadvantages  of  Campbell  process. 

Pages  132-133 
Chapter  XIV 

Condensing  by  Continuous  Process — Buflovak  rapid  circulation  evap- 
orator, construction,  operation;  continuous  concentrator,  descrip- 
tion, speed  of  agitator,  operation,  possibilities Pages  133-141 

Chapter    XV 

Condensed  Buttermilk — Manufacture,  separation  of  curd  by  gravity, 
evaporation  in  vacuo,  evaporation  by  hot  air  blast,  evaporation 
by  continuous  concentrator,  evaporation  by  centrifugal  separa- 
tion; packing;  composition;  uses. 

Condensed  Whey,  Myseost,  or  Primost Pages  141-146 


PART  IV 
FROM  FACTORY  TO  CONSUMER 

Chapter  XVI 
Stamping. 
Inspecting — Checking  the  work  of  the  sealers;  disposition  of  leaky 

cans;  importance  of  inspection. 

Labeling — Labeling  machines;  principle  of  labeling  machines;  wrin- 
kles and  rust  spots  on  labels. 
Packing — Marking  the  cases;  packing  condensed  milk  for  export. 

Pages  146-152 
Chapter  XVII 

Storage — Purpose  of  storing;  effect  of  storage  temperature;  advisabil- 
ity of  storing. 
Transportation  Pages  152-155 

Chapter  XVIII 

Markets — Market  prices  of  condensed  milk;  effect  of  World-War  on 
prices;  commercial  stock  Jan.  1,  1918;  exports  and  imports,  1911 
to  1918  Pages  155-161 

Chapter  XIX 

Chemical  Composition  of  Condensed  Milk— Sweetened  condensed  milk; 
evaporated  milk;  plain  condensed  bulk  milk;  concentrated  milk. 

Pages  162-172 
Chapter  XX 
Sanitary  Purity. 

Dietetic  Value  of  Condensed  Milk. 
Growth-Promoting  and  Curative  Properties Pages  173-178 

Chapter  XXI 

Condensed  Milk  Standards  and  Laws — Federal  standards  for;  sweet- 
ened condensed  milk;  evaporated  milk. 

Modified  standard;  difficulties  of  meeting  standard;  putting  com- 
position of  evaporated  milk  on  label. 


XII  CONDENSED  MILK  AND  MILK  POWDER 

Condensed  Skim  Milk. 

Explanatory  Notes  Concerning  Legality  of  Federal  Standards. 

Requirements  of  Composition  for  War  Contracts Pages  178-186 

Chapter  XXII 

Cost  of  Manufacture — General  Discussion. 

Cost  of  sweetened  condensed  milk  per  case. 

Cost  of  evaporated  milk  per  case Pages  186-190 


PART  V 
CONDENSED  MILK  DEFECTS,  THEIR  CAUSES  AND  PREVENTIONS 

Chapter  XXIII 
Classification  of  Defects. 
Defective  Sweetened  Condensed  Milk — Sandy,  rough  or  gritty;  settled; 

thickened  and  cheesy;  lumpy;  fermented;  rancid;  putrid;  metallic; 

brown Pages  190-215 

Chapter  XXIV 

Defective  Evaporated  Milk  and  Plain  Condensed  Bulk  Milk — Curdy; 
grainy;  separated  and  churned;  fermented,  acid  curd,  bitter  curd, 
gassy  fermentation. 

Swelled  cans  due  to  freezing;  swelled  cans  due  to  chemical  action; 
brown;  gritty;  metallic Pages  215-229 

Chapter  XXV 

Adulterations  of  Condensed  Milk — Skimming;  addition  of  artificial 
fats;  addition  of  commercial  glucose;  addition  of  bi-carbonate  of 
soda,  ammonium  hydroxide,  lime  water  and  other  alkali;  addition 
of  cream  of  tartar-;  addition  of  starch Pages  229-233 


PARRT  VI 
MANUFACTURE    OF   MILK    POWDER 

Chapter  XXVI 

Definition. 

Kinds. 

History  and  Development  of  Industry. 

Quality  of  Fresh  Milk. 

Description  of  Principal  Processes;  Wimmer  process;  Just-Hatmaker 
process;  Ekenberg  process;  Buflovak  process;  Campbell  process: 
Merrell-Gere  process .Pages  234-245 

Chapter  XXVII 
Packing  for  Market. 
Composition. 

Defects  of  Milk  Powders — High  water  content;  insoluble  milk  pow- 
ders; non-miscible  milk  powders;  rancid  milk  powders. 
Markets;  commercial  stocks  of  dried  milk Pages  245-248 


CONDENSED  MILK  AND  MILK  POWDER  XIII 

Chapter  XXVIII 

Dried  Buttermilk  and  Dried  Whey — Manufacture  of;  composition  of 

buttermilk  powders 
Malted  milk. 
Federal  Standards  for  Milk  Powders  and  Malted  Milk. .  .Pages  248-252 

Chapter  XXIX 

Standardization — Standardizing  fluid  milk  for  fat  and  milk  solids; 
standardizing  condensed  milk  for  fat,  solids  not  fat  and  total 
solids Pages  253-258 

Chapter  XXX 

Practical  Methods  of  Systematic  Examination  of  Product  for  Market- 
able Properties — Number  of  samples  needed;  frequency  of  exam- 
ination; technique  of  examination;  interpretation  of  results; 
systematic  examination  a  necessary  factor  of  economic  manu- 
facture   Pages  258-260 

Chapter  XXXI 

Chemical  Tests  and  Analyses — Milk — specific  gravity — total   solids — 
ash — total  nitrogen — casein  and   albumin — lactose — butterfat. 
Sweetened  Condensed  Milk — Preparation  of  sample — specific  grav- 
ity —  total    solids  —  ash  —  proteids — lactose — butterfat — sucrose — 
milk  solids. 

Evaporated  Milk — Preparation  of  sample — specific  gravity — total 
solids — tables  showing  total  solids,  when  Beaume  reading  and  per 
cent  fat  are  known — ash — proteids— lactose — butterfat. 
Milk  Powders  —  Total   solids — ash — proteids — lactose — sucrose  — 
butter  fat  Pages  261-283 

Chapter  XXXII 

Mojonnier  Test  for  Fat  and  Solids — List  of  equipment;  directions  for 
operating;  fresh  milk,  skim  milk,  whey  and  buttermilk;  sweetened 
condensed  milk,  evaporated  milk  and  plain  condensed  bulk  milk; 
powdered  milks  and  malted  milk Pages  283-294 

Chapter  XXXIII 

Detection  of  Adulterants  and  Preservatives — Extraneous  water;  skim- 
ming; extraneous  water  and  skimming;  artificial  coloring;  sucrose 
of  lime;  lime;  gelatin;  formaldehyde;  boric  acid;  benzoic  acid; 
salicylic  acid;  hydrogen  peroxide Pages  295-305 

Chapter  XXXIV 

Bacteriological  Analysis — Sampling,  dilutions,  preparation  of  media, 

plating,  incubation,  making  counts,  qualitative  determinations. 
Table  Showing  Legal  Standards  of  Dairy  Products  by  States 

Pages  307-311 


ACKNOWLEDGMENTS 


The  author  desires  to  express  his  high  appreciation  and  grat- 
itude to  Mr.  A.  W.  Milburn,  president  Borden's  Condensed  Milk 
Co.,  for  cuts  for  illustration  of  Gail  Borden  and  of  the  first  milk 
condensing  factory  in  the  United  States ;  to  Messrs.  Louis  Latzer, 
president  Helvetia  Condensed  Milk  Co.,  J.  P.  Meyenberg,  vice- 
president  Alpine  Evaporated  Cream  Co-,  and  to  John  F.  Mont- 
gomery, president  John  Wildi  Evaporated  Milk  Co.,  for  valuable 
biographic  data  concerning  the  early  history  of  the  evaporated 
milk  industry ;  to  Messrs.  D.  A.  Yoder,  president,  and  Howard 
S.  Mellott,  superintendent,  of  the  Ohio  Dairy  Co.,  for  gener- 
ous assistance  in  assembling  data  and  information  relating  to 
the  origin,  construction  and  operation  of  the  "Continuous  Con- 
centrator"; to  Mr.  T.  Mojonnier,  president  of  the  Mojonnier 
Bros.  Co.,  for  detailed  directions  for  the  operation  of  the  Mojon- 
nier test  and  other  phases  of  the  condensed  milk  industry;  to  Mr. 
R.  C.  Horlick,  president  of  Horlick's  Condensed  Milk  Co.,  for 
valuable  information  on  the  malted  milk  industry;  to  Mr.  S.  R. 
Park,  superintendent  Interstate  Milk  Products  Co.,  Sparta,  Wis., 
for  many  valuable  suggestions,  particularly  on  standardization ; 
to  Prof.  A.  C.  Anderson,  Michigan  Agricultural  College,  for 
valuable  data  on  war-time  cost  of  manufacture;  to  Dr.  C.  L. 
Alsberg,  chairman  of  Board  of  Editors,  for  permission  to  quote 
from  the  Journal  of  the  A.  O.  A-  C.,  and  to  the  following  manu- 
facturers of  machinery  and  supplies  related  to  the  manufacture 
of  condensed  milk  and  milk  powder  for  valuable  cuts  for  illus- 
tration in  the  text  and  for  their  generous  contributions  of  adver- 
tisements as  shown  at  the  conclusion  of  this  volume,  whose  kindly 
and  active  co-operation  made  possible  the  issuance  of  this  publi- 
cation; Alois  Aufrichtig  Copper  &  Sheet  Iron  Works;  A.  H. 


Barber  Creamery  Supply  Co.,  Bausch  &  Lomb  Optical  Co.,  Buf- 
falo Foundry  &  Machine  Co.,  By-Products  Recovery  Co.,  Cream- 
ery Package  Manufacturing  Co.,  Davis-Watkins  Dairymen's 
Manufacturing  Co.,  F.  G.  Dickerson  Co.,  The  Engineering  Co., 
J.  B.  Ford  Co-,  General  Laboratories,  Geuder,  Paeschke  &  Frey 
Co.,  Groen  Manufacturing  Co-,  Hamilton  Brass  &  Copper  Works, 
Arthur  Harris  &  Co.,  Jalco  Motor  Co.,  Jensen  Creamery  Machin- 
ery Co.,  Mojonnier  Bros.  Co.,  Louis  F.  Nafis,  Inc.,  The  Pfaudler 
Co.,  C.  E.  Rogers,  E.  H.  Sargent  &  Co.,  Schaefer  Mfg.  Co.,  The 
Sharpies  Separator  Co.,  The  Simpson-Doeller  Co.,  L.  Sonneborn 
Sons,  Inc.,  Stevenson  Cold  Storage  Door  Co.,  Sturges  &  Burn 
Mfg.  Co.,  C.  J.  Tagliabue  Mfg.  Co.,  Torsion  Balance  Co-,  The 
Vulcan  Detinning  Co. 


Complete  Milk  Condensing  Unit 


for 


Dairy  Schools 
and  Experimental  Laboratories 


The  dairy  school  is  the  manufactory  of  dairy 

knowledge,  the  clearing  house  of  dairy 

thought,  and  the  distributor y  of  the 

dairy  gospel. 


PART  I. 
CONDENSED  MILK 

CHAPTER  I. 
DEFINITION 

Condensed  milk  is  cow's  fresh  milk  from  which  a  considerable 
portion  of  the  water  has  been  evaporated  and  to  which  sucrose  may 
or  may  not  have  been  added. 

There  are  chiefly  two  classes  of  condensed  milk,  namely,  sweet- 
ened and  unsweetened.  Both  reach  the  market  in  hermetically 
sealed  tin  cans  intended  for  direct  consumption,  and  in  bulk,  in- 
tended for  bakers,  confectioners  and  ice  cream  manufacturers. 

A  portion  of  the  condensed  milk  on  the  market  is  made  from 
the  chief  by-products  of  milk,  skim  milk  and  buttermilk.  Condensed 
skim  milk  supplies  the  same  markets  as  condensed  whole  milk  sold 
in  bulk.  Condensed  buttermilk  furnishes  a  valuable  chicken  feed. 
It  has,  also,  been  recommended  for  medicinal  purposes. 

HISTORY  AND  DEVELOPMENT  OF  INDUSTRY 

Invention  of  Process. —  Condensed  milk  is  the  child  of  the 
nineteenth  century.  Its  origin  does  not  date  back  far,  and  its 
innovation  and  rapid  development  stand  in  sharp  contrast  to  those  of 
the  manufacture  of  butter  and  cheese,  industries  to  which  reference 
is  made  in  the  Old  Testament1  and  the  evolution  of  which  has  been 
very  gradual.  Notwithstanding  the  newness  of  this  product,  its 
manufacture  has  assumed  such  proportions  that  today  it  occupies  a 
prominent  place  am6ng  the  leading  branches  of  dairy  manufactures. 

The  condensed  milk  industry  was  introduced  at  about  the  same 
time  as  the  factory  system  of  the  butter  and  cheese  industry ;  al- 
though, for  many  years  before  the  invention  of  a  successful  process 
of  condensing  milk,  methods  had  been  sought  to  preserve  milk. 


1  Book  of  Genesis,  C.  18,  V.  8:  "And  he  took  butter  and  milk  and  the  calf  he 
had  dressed  and  set  it  before  them." 

Book  of  Job,  C.  10,  V.  10.  "Hast  thou  not  poured  me  out  lik«  milk  and 
curdled  me  like  cheese." 


18  :  .  V"   :    /    HSTORY  AND 


.iJ-  Borden,  the  inventor  of  the  manufacture 
of  condensed  milk,  is  said  to  have  experimented  some  ten  years 
before  he  finally  decided  that  a  semi-fluid  state,  produced  by  evap- 
oration in  vacuo,  was  the  best  form  of  preservation.  He  first 
applied  for  a  patent  in  1853,  but  it  was  not  until  three  years  later 
that  the  Patent  Office  appreciated  the  originality  and  value  of  his 


Fig.  2.     Gail   Borden 

claim  sufficiently  to  grant  him  a  patent.  In  August,  1856,  he  was 
awarded  a  patent  on  his  process  both  by  the  United  States  and  by 
England. 

In  his  application  Mr.  Borden  says  i1 

"I  am  aware  that  sugar,  and  various  extracts,  have  been  and 
are  now  concentrated  in  vacuo  under  a  low  degree  of  heat,  to  pre- 
vent discoloration  or  burning.  I  do  not  claim  concentrating  milk  in 
a  vacuum  pan  for  such  a  purpose,  my  object  being  to  exclude  the 
air  from  the  beginning  of  the  process  to  the  end,  to  prevent  incipient 
decomposition.  This  is  important  and  I  claim  the  discovery." 


*•  "A  Brief  Sketch  of  Gail  Borden"  by  S.  L.  Goodale,  Secretary  Maine  State 
Board  of  Agriculture,  1872. — Courtesy  of  Borden's  Condensed  Milk  Company. 


HISTORY  AND  DEVELOPMENT  19 

The  claim,  United  States  Patent,  August,  1856,  is  in  the  fol- 
lowing words: 

"Producing  concentrated  sweet  milk  by  evaporation  in  vacuo, 
substantially  as  set  forth, — the  same  having  no  sugar  or  other 
foreign  matter  mixed  with  it." 

Since  the  introduction  of  the  process  of  milk  condensing,  in- 
vented and  patented  by  Borden,  numerous  modifications  of  the 
process,  as  well  as  entirely  different  processes,  have  been  invented 
in  this  country  and  abroad.  The  most  characteristic  among  these 
are:  condensation  by  refrigeration,  by  centrifugal  force,  by  boiling 
under  atmospheric  pressure,  by  passing  hot  air  through  milk,  etc. 
Most  of  these  new  processes  have  not  proved  commercially  satis- 
factory, with  the  result  that  the  principle  of  the  process,  originally 
invented  by  Gail  Borden,  and  which  consists  of  condensing  the  milk 
in  vacuo  to  a  semi-fluid  liquid,  is  still  made  use  of  in  the  manufacture 
of  the  great  bulk  of  condensed  milk  produced,  both  in  this  country 
and  abroad. 

While  the  claim  of  the  patent  granted  Gail  Borden  was  that  of 
"producing  concentrated  sweet  milk  by  evaporation  in  vacuo  without 
the  admixture  of  sugar  or  other  foreign  matter,"  records  show  that 
Gail  Borden  manufactured  sweetened  condensed  milk,  sold  under 
the  famous  Eagle  Brand  label  as  early  as  1856.  The  first  adver- 
tisement by  Borden  of  unsweetened  condensed  milk  was  recorded  in 
Leslie's  Weekly,  May  22,  1858.  It  reads  as  follows : 

"BORDEN'S  CONDENSED  MILK.  Prepared  in  Litchfield  County, 
Conn.,  is  the  only  milk  ever  concentrated  without  the  admixture  of 
sugar  or  some  other  substance  and  remaining  easily  soluble  in  water. 
It  is  simply  Fresh  Country  Milk,  from  which  the  water  is  nearly 
all  evaporated,  and  nothing  added.  The  Committee  of  the  Academy 
of  Medicine  recommend  it  as  'an  article,  that,  for  purity,  durability 
and  economy,  is  hitherto  unequalled  in  the  annals  of  the  milk  trade.' 

"One  quart,  by  the  addition  of  water,  makes  two  and  a  half 
quarts, — equal  of  cream,  five  quarts  rich  milk  and  seven  quarts 
good  milk. 

"For  sale  at  173  Canal  Street,  or  delivered  at  dwellings  in  New 
York  or  Brooklyn  at  25  cents  per  quart." 

Development  of  Industry. —  The  beginning  was  small,  the 
process  crude  and  the  product  imperfect.  Not  until  the  strenuous 
years  of  the  war  of  Secession  did  the  value  and  usefulness  of  con- 


20 


HISTORY  AND 


Fig  3. 

The  first  condensed  milk  factory  In 
America,  Wolcottville,  Conn. 


densed  milk  as  a  commodity  become 
fully  recognized.  During  the  Civil 
War  there  was  a  great  demand  for 
this  product  and  from  that  time  on 
the  industry  grew  with  great  rapid- 
ity. 

The  first  factory  was  operated 
by  Gail  Borden  in  Wolcottville, 
Litchfield  county,  Connecticut,  in 
the  summer  of  1856,  but  disap- 
pointed in  not  obtaining  means, 
nothing  was  accomplished.  A  sec- 
ond attempt  was  made  at  Burrville, 

five  miles  distant,  in  1857,  by  a  company  consisting  of  the  owners  of 
the  patent.  A  small  quantity  of  milk  was  here  successfully  con- 
densed and  its  introduction  into  New  York  began.  Although 
admitted  by  all  to  be  superior  to  any  before  made,  it  was  slow  in 
meeting  with  sales  proportional  in  magnitude  to  the  expenses  in- 
curred. Yielding  to  the  monetary  revulsion  of  that  year  the  company 
suspended  operations,  leaving  Mr.  Borden  liable  for  bills  drawn,  on 
which  he  was  sued. 

It  was  not  until  February,  1858,  when  Mr.  Borden  (with  the 
other  owners  of  the  patent)  associated  himself  with  Jeremiah  Mil- 
bank,  Esq.,  who  advanced  money  to  revive  the  business,  that  he 
could  be  said  to  enjoy  adequate  means  to  develop  his  invention  and 
at  which  time  the  New  York  Condensed  Milk  Company  was  formed. 
Abandoning  Burrville,  the  new  company  established  work  on  a  more 
extensive  scale  in  Wassaic,  Duchess  county,  New  York,  in  1860. 
In  1865,  extensive  works  were  erected  at  Elgin,  Illinois.  Borden's 
Condensed  Milk  factories  today  number  upwards  of  fifty,  extending 
from  Maine  to  Washington  State  as  well  as  into  Canada.  The 
New  York  Condensed  Milk  Company  was  incorporated  in  New 
Jersey  in  1860  and  in  New  York  in  1870.  This  company  was 
succeeded  by  Borden's  Condensed  Milk  Company  which  was  incor- 
porated in  New  Jersey  in  1899. 

In  the  sixties  of  the  last  century,  the  Anglo- Swiss  Condensed 
Milk  Company  was  organized  in  Switzerland  under  the  leadership 
of  Charles  A.  Page,  then  United  States  Consul  at  Zurich,  Switzer- 
land, and  his  brother  George  H.  Page,  and  with  the  assistance  of 


HISTORY  AND  DEVELOPMENT 


21 


Swiss  and  English  capital.  The  first  factory  of  that  company  was 
built  and  operated  in  1866  at  Cham,  Lake  Zug,  Switzerland,  under 
the  direction  of  George  H.  Page,  who  was  its  president  until  1898, 
when  he  died. 

This  company  prospered  and  grew  rapidly  in  Europe.  In  the 
eighties  of  the  last  century  it  invaded  the  United  States,  where  it 
built  and  operated  several  large  factories  in  New  York,  Wisconsin 
and  Illinois.  The  American  factories  were  managed  by  David  Page 
and  William  B.  Page,  brothers  of  George  H.  Page.  In  1902  the 
Anglo-Swiss  Condensed  Milk  Company  sold  its  entire  American 


I 


BKMSCaid  iSsss 


Morey    Gondensery,    North    Prairie,    Wis. 

interests,  factories  and  business,  to  Borden's  Condensed  Milk  Com- 
pany. In  1904  the  Anglo-Swiss  Condensed  Milk  Company  consoli- 
dated with  Henry  Nestle,  of  Vevey,  Lake  Geneva,  Switzerland,  an- 
other successful  manufacturer  of  condensed  milk.  The  company 
which  is  now  known  as  the  Nestle-Cham  Condensed  Milk  Company, 
is  operating  some  twenty  large  condensed  milk  factories  in  European 
countries,  with  headquarters  at  Cham,  Switzerland. 

Up  to  the  early  eighties  of  the  last  century,  sweetened  con- 
densed milk  was  the  only  condensed  milk  that  was  put  on  the  market 
and  sold  in  hermetically  sealed  cans,  while  unsweetened  condensed 
milk  was  manufactured  and  sold  open,  largely  direct  to  the  con- 
sumer, in  a  similar  way  as  market  milk.  The  purity  and  keeping 
quality  of  this  unsweetened  condensed  milk,  however,  were  greatly 
superior  to  market  milk. 

Early  in  1885  the  Helvetia  Milk  Condensing  Company  was 
organized  at  Highland,  Illinois.  This  company  confined  its  efforts 
exclusively  to  the  manufacture  of  evaporated  milk  (unsweetened 


22  HISTORY  AND  DEVELOPMENT 

condensed  milk,  sterilized  by  heat  and  sold  in  hermetically  sealed 
cans).  While,  for  several  years  before  the  organization  of  this 
company,  the  possibilities  of  producing  a  sterile  unsweetened  con- 
densed milk  were  essayed  in  laboratory  investigations  by  scientists, 
and  while  simultaneously  with  the  commencement  of  operations  of 
this  company,  several  other  companies  also  experimented  on  this 
form  of  condensed  milk,  the  Helvetia  Milk  Condensing  Company 
was  the  first  organization  that  succeeded  in  producing  a  marketable 
unsweetened  condensed  milk  that  was  sterile  and  would  keep  in- 
definitely. 


Fig.  5.     John    B.   Meyenberg 

The  rudiments  of  the  process  of  evaporated,  sterilized  milk 
were  introduced  by  Mr.  John  B.  Meyenberg,  a  native  of  Switzer- 
land, who  formerly  was  operator  in  the  mother  plant  of  the  Anglo- 
Swiss  Condensed  Milk  Co.  at  Cham,  Switzerland.  Mr.  Meyenberg, 
being  a  man  with  an  inventive  turn  of  mind,  experimented  on  the 
evaporation  and  sterilization  of  milk,  during  the  years  1880  to  1883. 
As  the  result  of  these  experiments  he  decided  that  it  was  possible 
to  preserve  milk,  without  the  aid  of  sugar.  Migrating  to  this 
country,  he  applied  for,  and  was  granted  a  patent  on  his  idea  of 
preserving  milk  by  sterilization,  by  the  United  States  Government 
in  1884  (Patent  No.  308,422),  and  again  in  1887  (Patent  No. 
358,213).  Mr.  Meyenberg  was  also  granted  patent  rights  (Patent 
No.  308,421)  on  apparatus  for  preserving  milk. 


HISTORY  AND  DEVELOPMENT  23 

Attracted  to  Highland,  Illinois,  by  reason  of  its  large  Swiss 
population,  on  the  representations  of  Mr.  A.  J.  Pagan,  a  leading 
Highland  citizen,  who  brought  Mr.  Meyenberg  to  Highland  and 
introduced  him  to  the  community,  Mr.  Meyenberg  associated  himself 
with  Mr.  John  Wildi,  then  a  merchant  of  Highland,  who  at  once 
took  a  leading  part  in  the  organization  of  the  Helvetia  Milk  Con- 
densing Co.,  early  in  the  year  1885.  Mr.  Meyenberg  served  as  the 
technical  manager  for  the  first  year,  after  which  he  severed  his 
connections  with  this  company  and  became  engaged  in  the  promo- 
tion of  other  evaporated  milk  factories  in  the  middle  west,  and  on 
the  Pacific  Coast.  Mr.  Meyenberg  died  in  1914. 

During  the  first  year  of  its  existence,  operations  of  the  Helvetia 
Milk  Condensing  Company  were  suspended  a  number  of  times,  both 
on  account  of  difficulties  encountered  in  the  technique  of  successful 
manufacture  and  also  for  financial  reasons.  In  an  endeavor  to  place 
the  company  on  a  technically  and  commercially  successful  basis,  the 
board  of  directors  took  charge  of  the  work  with  Mr.  Louis  Latzer 
as  technical  manager,  and  the  first  half  of  the  second  year  was 
mostly  devoted  to  experimental  work.  During  the  third  year,  inter- 
ruptions in  the  operations  were  only  slight  and  after  that  the  com- 
pany operated  continuously  and  successfully  until  the  panic  of 
1893,  which  marked  the  last  suspension  of  business  and  which  was 
due  to  the  strained  commercial  conditions  that  prevailed  throughout 
the  country. 

The  first  board  of  directors  of  this  company  was  composed  of 
Dr.  Knoebel,  John  Wildi,  George  Roth,  Fred  Kaeser  and  Louis 
Latzer,  with  Dr.  Knoebel  as  president  and  Mr.  Wildi  as  secretary 
and  treasurer,  and  business  manager.  In  1888  Mr.  Latzer  became 
president,  which  position  he  is  holding  to  the  present  day.  In  1907 
Mr.  Wildi  severed  his  connection  and  organized  the  John  Wildi 
Evaporated  Milk  Co.  with  headquarters  in  Columbus,  Ohio.  Mr. 
Wildi  died  in  1910. 

The  early  development  and  the  vicissitudes  through  which  this 
pioneer  company  in  the  evaporated  milk  business  passed  are  most 
instructively  expressed  by  its  president,  Mr.  Latzer : 

"Very  little  of  the  product  turned  out  the  first  two  years  would 
now  pass  as  standard  goods.  About  the  third  year,  after  more 
knowledge  of  the  physical  and  chemical  properties  of  milk  and 
after  the  introduction  of  the  practice  of  fractional  sterilization,  had 


24  HISTORY  AND 

solved  the  keeping  properties  and  had  improved  the  physical  condi- 
tion of  the  product,  we  felt  that  the  industry  had  come  to  stay. 
After  we  had  gained  more  knowledge  and  experience,  and  a  lower 
standard  of  the  product  was  adopted  by  the  industry,  the  practice 
of  fractional  sterilization  was  abandoned  for  economic  reasons. 

"The  commercial  part  of  the  business  also  had  its  trials  and 
tribulations  in  introducing  a  new  and  comparatively  inferior  product 
of  comparatively  high  cost,  and  to  overcome  the  prejudices  of  both 
the  trade  and  the  medical  profession. 

"The  problem  thus  confronting  the  company  was  to  improve 
the  product,  decrease  its  cost  and  improve  selling  methods  at  the 
least  possible  cost." 

At  first  this  unsweetened  condensed  milk,  of  relatively  thin 
consistency  and  pregnant  with  the  cooked  flavor  resulting  from  its 
exposure  to  high  sterilizing  temperatures,  failed  to  appeal  to  the 
public,  who  had  become  accustomed  to  the  use  of  the  sweet,  thick 
and  semi-fluid  sweetened  condensed.  But  of  late  years  the  demand 
for,  and  the  manufacture  of  this  product,  evaporated  milk,  has 
increased  rapidly,  until  today,  in  this  country,  its  output  by  far 
exceeds  that  of  sweetened  condensed  milk. 

Originally  this  unsweetened  sterilized  condensed  milk  was 
labeled  and  sold  under  the  name  of  "Evaporated  Cream."  The 
Federal  Food  &  Drugs  Act  of  1906  caused  the  name  "Evaporated 
Cream"  to  be  changed  to  "Evaporated  Milk." 

A  further  important  step  in  the  development  of  the  manufac- 
ture of  condensed  milk  occurred  with  the  introduction  of  the  Con- 
tinuous Concentrator,  which  machine  was  developed  by  the  By- 
Products  Recovery  Co.,  of  Toledo,  Ohio.  This  company  was  or- 
ganized in  1913  and  their  machine  and  process  are  covered  by 
numerous  United  States  patents.  The  principle  upon  which  the 
Continuous  Concentrator  is  constructed  and  operates  is  as  follows: 

"To  rapidly  move  a  film  in  layer  formation  within  a  cylinder 
having  a  heated  surface,  having  means  for  escaping  vapors  and 
means  for  keeping  the  surface  bright  and  clean,  circumferentially 
and  from  the  point  of  inlet  to  the  point  of  outlet." 

The  Continuous  Concentrator  in  its  present  improved  form  has 
reached  a  state  of  perfection  that  renders  this  machine  applicable 
for  the  commercial  manufacture  of  the  diverse  forms  of  condensed 
milk  and  milk  by-products. 


HISTORY  AND 


25 


The  simplicity  and  economy  of  the  equipment  involved,  the 
simplicity  and  rapidity  of  the  process  and  the  fact  that  no  water 
is  required  for  condensing  the  escaping  vapors,  are  decided  advan- 
tages over  the  condensation  in  vacuo.  Already  the  demand  for 
these  concentrators  among  condenseries  and  ice  cream  factories  is 
very  great.  This  process  lends  itself  admirably  to  the  establishment 
and  operation  of  small  local  condenseries  and  milk  shipping  stations 
where  milk  is  condensed  and  then  shipped  for  packing  and  steriliza- 
tion to  concentration  plants. 

In  this  country,  as  well  as  in  Canada  and  Europe,  the  condensed 
milk  industry  grew  rapidly.  Every  succeeding  decade  marked  the 
organization  of  new  companies  and  the  erection  of  new  factories 
until  today,  there  are  milk  condensing  factories  in  nearly  every 
civilized  country  within  the  dairy  belt. 

ANNUAL  OUTPUT  OF  CONDENSED  MILK  IN  THE  UNITED  STATES 
1899-1917,  INCLUSIVE 


Years 

Total 
condensed 
milk 

Sweetened 
condensed 
Milk 

Unsweetened 
condensed 
Milk 

1899— 
Pounds1 

186,921,787 

(5) 

(5) 

Dollars1  ..... 

11,888,792 

(5) 

(5) 

1904- 
Pounds1  

308,485,182 

198,355,189 

110,129,993 

Dollars1  
1909— 
Pounds1 

20,149,282 
494,796,544 

13,478,376 
214,518,310 

6,670,906 
280,278,234 

Dollars1  

33,563,129 

17,345,278 

16,217,851 

1914— 
Pounds2  

883,112,901 

(5) 

(5) 

Dollars3 

58,011,677 

(5) 

(5) 

1917- 
Pounds2  
Dollars4  ..  . 

975,000,000 
106,000,000 

(5) 
(5) 

(5) 
(5) 

1  United  States  Census  Report  for  1910. 

2  United   States  Dairy  Division,   by  Correspondence. 

3  Value  estimated  at  $3.40  per  case. 
*  Value  estimated  at  $5.50  per  case. 

5  Not  reported  separately. 


26  HISTORY  AND  DEVELOPMENT 

The  above  figures  serve  to  emphasize  the  rapid  growth  which 
the  condensed  milk  industry  has  enjoyed  during  the  last  decade. 
The  total  output  of  condensed  milk  in  1917  was  975,000,000  pounds, 
estimated  at  a  value  of  $106,000,000.00.  Calculating  the  ratio  of 
concentration  at  2.5  to  1,  this  output  represents  the  utilization  of 
2,437,000,000  pounds  of  fluid  milk  for  the  condensed  milk  industry. 
The  total  production  of  fluid  milk  in  the  United  States  in  1917  was 
84,611,350,000  pounds,  of  which  2.9  per  cent  were  manufactured 
into  condensed  nxilk. 

The  above  figures  largely  represent  canned  condensed  milk 
only.  Within  recent  years,  the  manufacture  of  condensed  milk 
sold  in  bulk,  especially  to  the  ice  cream  trade,  has  increased  enor- 
mously. If  this  bulk  condensed  milk  were  included  in  the  above 
figures,  the  amount  shown  for  the  total  output  would  be  materially 
augmented. 

A  new  and  unprecedented  impetus  was  given  the  condensed 
milk  industry  in  America  by  the  advent  of  the  World  War.  The 
concentration  of  the  product,  its  wholesomeness  and  high  food 
value,  the  serviceableness  of  its  package  and  its  great  keeping 
quality  render  it  indispensable  as  a  food  for  the  army  and  navy  as 
well  as  for  the  civilian  population  of  the  warring  nations  in  its 
dire  need  for  food.  In  this  great  crisis  in  which  the  food  supply 
of  the  nations  of  the  earth  is  playing  a  most  important  role,  con- 
densed milk  has  proved  its  worth  and  the  demand  for  this  com- 
modity has  increased  to  tremendous  proportions.  This  demand  has 
been  readily  responded  to  by  the  industry  on  the  American  con- 
tinent and  has  resulted  in  a  vast  increase  of  the  output  of  condensed 
milk  and  in  the  erection  of  many  new  and  large  factories  within 
the  short  span  of  the  war. 

In  1899,  there  were  in  operation  in  this  country  about  fifty 
factories  manufacturing  condensed  milk,  distributed  over  fourteen 
different  states,  New  York  and  Illinois  leading  the  list  by  over  50 
per  cent.  In  1904,  the  Government  estimated  the  total  number  of 
condenseries  in  operation  at  eighty-seven.  In  1914,  there  were  in 
the  United  States  over  two  hundred  milk  condensing  factories, 
distributed  over  twenty-three  different  states,  as  shown  on  the 
following  page : 


HISTORY  AND  DEVELOPMENT  27 

DISTRIBUTION  OF  MILK  CONDENSING  FACTORIES  IN  UNITED  STATES 

IN  1914 

States  Number  of  Factories 

Arizona  1 

California  7 

Colorado  1 

Illinois  39 

Indiana  9 

Iowa  3 

Kansas  4 

Kentucky  1 

Maine  1 

Maryland  3 

Massachusetts  1 

Michigan  12 

Missouri  2 

New  Jersey  6 

New  York  54 

North  Dakota  1 

Ohio  19 

Oregon  6 

Pennsylvania  20 

Utah  6 

Vermont  4 

Washington  .  14 

Wisconsin  26 


Total  23  240 

The  above  distribution  of  milk  condenseries  has  undergone  con- 
siderable change  since  the  beginning  of  the  war.  In  many  states 
new  factories  have  been  erected  and  in  numerous  instances  cream- 
eries and  cheese  factories  have  been  converted  into  condenseries. 
In  the  State  of  Wisconsin  alone  the  number  of  condenseries  has 
risen  from  26  in  1914  to  52  in  1918. 

Other  countries  in  which  the  condensed  milk  industry  has  made 
rapid  progress  are :  Canada,  Australia,  New  Zealand,  Switzerland, 
Germany,  England,  Ireland,  Holland,  Sweden,  Norway,  Austria, 
Russia,  Japan  and  India. 


28  ESSENTIALS  OF  SUITABLE  LOCATIONS 

CHAPTER  II. 

ESSENTIALS  OF  SUITABLE  LOCATIONS  FOR  MILK 
CONDENSING  FACTORIES 

Unlike  the  establishment  of  creameries  and  cheese  factories, 
the  building  of  condenseries  and  the  installing  of  the  necessary  ma- 
chinery involve  the  investment  of  large  capital.  There  is  need  of 
a  substantial  building  and  of  expensive  machinery.  The  supplies 
are  numerous  and  must  be  purchased  in  larger  quantities  before 
the  returns  from  the  sale  of  the  manufactured  product  are  avail- 
able. It  is  estimated  that  it  takes  from  three  to  six  months  before 
the  condensed  milk  reaches  the  consumer.  This  holds  true  espec- 
ially in  the  case  of  canned  goods.  The  fixed  expenses  also  are  com- 
paratively heavy,  and  do  not  materially  change  with  a  decrease  or 
increase  in  the  milk  supply. 

All  of  these  facts  emphasize  the  importance  of  locating  the 
factory  in  a  territory  most  suitable  for  economic  manufacture,  to 
guard  against  heavy  loss  which  would  naturally  result  in  localities 
unfavorable  to  the  industry. 

The  chief  factors  to  be  considered  in  this  connection  are: 
Milk  supply 
Water  supply 
Transportation    facilities. 
Other  conditions. 

Milk  Supply. —  A  large  supply  of  milk  with  possibilities  for 
extending  the  milk  supply  territory  is  the  first  essential.  The  con- 
densery  must  have  milk  to  do  business.  The  locality  in  which  it  is 
located  must  be  adapted  for  the  production  of  large  quantities  of 
milk;  it  must  be  a  dairy  country  where  reasonably  large  herds  are 
kept.  Other  things  being  equal,  the  larger  the  milk  supply,  the 
lower  the  cost  of  manufacture.  Where  the  milk  supply  drops  be- 
low fifteen  thousand  pounds  of  milk  daily,  profitable  manufacture 
becomes  difficult.  Territories  of  gathered  cream  creameries  are 
usually  not  very  desirable.  The  farmers  generally  have  small  herds 
and  are  not  inclined  to  haul  their  milk  daily.  They  prefer  to  take 
their  cream  to  the  creamery  once  or  twice  per  week,  or  whenever  it 
is  convenient  for  them  to  do  so.  Again,  they  appreciate  the  feed- 
ing value  of  the  skim  milk  and  depend  on  the  skim  milk  to  raise 


ESSENTIALS  OF  SUITABLE;  LOCATIONS  29 

their  young  stock  and  pigs.  When  they  take  their  milk  to  the  con- 
densery,  there  is  no  skim  milk  nor  buttermilk  left  for  feeding  pur- 
poses. 

The  presence  of  whole  milk  creameries  and  cheese  factories 
renders  a  locality  most  attractive  for  the  establishment  of  milk 
condenseries.  The  farmers  usually  have  reasonably  large  herds,  they 
are  accustomed  to  take  reasonable  care  of  their  milk  and  to  haul 
it  to  the  factory  daily,  and  the  condensery  prices  are  generally  high 
enough  above  the  creamery  or  cheese  factory  prices  to  induce  the 
fanners  to  patronize  the  condensing  factory. 

Territories  in  close  proximity  of  large  consuming  centers, 
though  dairying  may  have  reached  a  high  state  of  development,  are 
not  desirable,  owing  to  the  continuous  and  growing  demand  for 
fresh  milk.  Competition  of  this  kind  means  high  prices,  which  no 
business  tactics  are  capable  of  modifying. 

Water  Supply. — The  value  to  the  milk  condensing  plant  of  a 
generous  and  never-failing  supply  of  clean,  cool  water  cannot  be 
overestimated.  The  folly  of  erecting  condenseries  without  first 
ascertaining  the  water  supply  has  in  some  instances  compelled  milk 
condensing  companies  to  abandon  new  plants,  merely  because  of 
lack  of  water. 

In  addition  to  the  water  used  in  the  boilers  and  for  washing 
purposes,  large  amounts  of  water  are  necessary  for  condensing  and 
for  cooling  the  condensed  milk.  It  is  estimated  that  the  condensa- 
tion of  one  pound  of  fresh  milk  requires  about  three  gallons  of 
water. 

The  water  must  be  pure.  In  spite  of  all  precautions,  it  will 
come  in  contact,  more  or  less,  with  the  milk.  Though  all  apparatus 
and  utensils  holding  and  conveying  milk  and  condensed  milk  may 
be  thoroughly  steamed  after  rinsing  with  water,  there  are  untold 
channels  through  which  the  milk  may  become  contaminated  with 
polluted  water.  Frequently,  while  the  milk  is  condensing,  the  vac- 
uum pump  accidentally  stops.  If  the  processor  fails  to  immediately 
shut  off  the  water  supplying  the  condenser,  water  will  pour  back 
from  the  condenser  into  the  milk  in  the  vacuum  pan.  In  the  case 
of  filthy,  polluted  water,  the  entire  batch  may  be  ruined.  Again, 
the  pan  is  usually  rinsed  between  batches  and,  if  the  water  used  is 
unclean,  it  will  contaminate  the  milk  of  the  succeeding  batch. 


30  ESSENTIALS  OF  SUITABLE  LOCATIONS 

Finally,  when  the  heavy  40-quart  cans  filled  with  condensed  milk 
are  set  into  the  cooling  tank,  water  frequently  splashes  over  into 
the  cans.  Here  again  the  quality  of  the  condensed  milk  is  jeopar- 
dized, unless  the  water  used  is  pure. 

The  water  must  be  cold.  The  colder  the  water  the  more  sat- 
isfactory is  the  operation  of  the  vacuum  pan.  If  the  temperature 
of  the  "water  used  in  the  condenser  rises  much  above  65  degrees  F., 
the  process  of  condensing  becomes  difficult.  Cold  water  is  essen- 
tial, also,  for  the  prompt  and  proper  cooling  of  the  condensed 
milk. 

Transportation  Facilities. — It  is  essential  that  the  factory  have 
access  to  one  or  more  railway  lines. 

While,  for  reasons  discussed  under  "Milk  Supply,"  it  is  not 
advisable  to  erect  a  factory  in  too  close  proximity  to  large  consum- 
ing or  railway  centers,  it  is  equally  undesirable  to  choose  a  conden- 
sery  site  where  transportation  facilities  are  poor. 

Where  access  to  one  railroad  only  can  be  had,  the  factory  is 
at  the  mercy  of  that  road.  Experience  has  shown  that  monopoly 
of  transportation  usually  means  a  low  standard  of  efficiency  of 
service  and  high  freight  rates.1  On  the  other  hand,  competition  in- 
volves a  struggle  for  the  survival  of  the  fittest,  and  it  offers  the 
public  all  the  inducements  that  business  ingenuity  and  enterprise 
can  produce.  Where  two  or  more  transportation  companies  are 
after  the  business  of  the  same  manufacturing  concern,  they  will 
generally  leave  nothing  undone  in  the  way  of  accommodations  and 
low  rates  to  please  the  manufacturer.  The  result  is  that  the  man- 
ufacturer enjoys  the  advantages  of  efficient  service,  good  accom- 
modations and  reasonable  freight  rates.1 

This  is  a  factor  which  the  condensery  cannot  afford  to  over- 
look, as  the  freight  charges  are  a  very  conspicuous  item  in  the  ex- 
pense account  of  the  milk  condensing  business.  A  part  of  the  fresh 
milk  may  have  to  be  shipped  to  the  factory  by  rail,  all  the  finished 
product  must  leave  the  factory  by  rail  and  the  condensery  is  de- 
pendent on  the  railway  for  its  raw  materials  and  supplies,  such  as 
sugar,  tinplate,  solder,  box  shooks,  barrels,  labels,  oil,  rosin,  gaso- 
line, coal,  etc.  Prompt  and  efficient  transportation  is  essential. 


1  The  matter  of  freight  rates  is  now  largely  regulated  by  the  Federal  De- 
partment of  Transportation. 


BUILDING  AND  EQUIPMENT  31 

Undue  delays  may  cause  the  condensery  serious  inconvenience  and 
loss,  and  may  result  in  the  cancelling  of  important  orders. 

Other  Conditions. — The  removal  of  the  sewage  of  the  factory 
is  important.  It  may  be  possible  for  the  factory  to  connect  with 
the  town  or  city  sewer,  in  which  case  the  problem  is  easily  solved. 
Where  this  is  not  possible,  a  site  along  a  creek,  river,  pond  or  lake 
may  offer  effective  means  to  take  care  of  the  condensery  sewage. 
Where  no  such  natural  depository  is-available,  the  elevation  of  the 
site  should  be  sufficient  to  carry  off  the  sewage  far  enough  from 
the  factory  to  insure  the  plant  against  foul  odors  and  unsanitary 
conditions.  In  the  absence  of  all  of  these  avenues  for  the  disposal 
of  the  sewage,  a  properly  laid-out  system  of  septic  tanks  with  effi- 
cient filter  beds  may  serve  the  purpose. 

Where  possible,  it  is  advisable  to  take  advantage  of  hillsides, 
affording  natural  means  to  arrange  and  operate  the  factory  on  the 
gravity  plan.  , 

BUILDING  AND  EQUIPMENT 

Material  of  Construction. — Since  the  establishment  of  a  milk 
condensing  factory  involves  the  investment  of  considerable  capital, 
those  willing  to  invest  must  have  faith  in  the  permanency  of  the 
business.  For  a  permanent  business,  a  building  substantially  con- 
structed is  the  most  economical.  Most  of  the  factories  belonging 
to  the  most  reputable  concerns  are  built  very  substantially.  How- 
ever, there  are  in  this  country  condensing  factories  in  the  construc- 
tion of  which  cheapness  was  the  governing  factor.  Many  of  these 
cheap  factories  are  the  work. of  unscrupulous  promoters,  whose 
ambition  it  is  to  convince  men  of  wealth  or  farmnig  communities 
of  the  "enormous"  profits  possible  in  the  manufacture  of  condensed 
milk,  and  to  induce  them  to  invest  large  sums  of  money  in  the  con- 
densed milk  industry.  By  skillful  manipulation  these  promoters 
frequently  secure  "fat  rake-offs"  on  every  purchase  of  machinery 
and  on  every  contract  of  labor,  occasionally  on  every  sale  of  the 
product.  Their  victims  pay  exorbitant  prices  for  a  first  class  build- 
ing and  most  up-to-date  equipment,  and  often  receive  a  shack  barely 
strong  enough  to  stand  up  under  its  own  weight,  and  equipment  of 
inadequate  capacity. 


32 


BUILDING  AND  EQUIPMENT 


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BUILDING  AND  EQUIPMENT  33 

It  is  beyond  the  realm  of  this  volume  to  furnish  detailed  speci- 
fications and  plans  for  the  construction  of  condensed  milk  factories. 
Such  information  would  be  of  comparatively  little  value,  as  such 
details  must  of  necessity  vary  with  locality,  capacity  of  prospective 
plant,  type  of  equipment,  system  of  operation  and  preferences  of 
individual  owners.  Such  details  are  best  decided  on  and  worked 
out  for  each  individual  factory  separately  and  when  needed.  There 
are  a  few  fundamental  principles,  however,  which  apply  to  all  fac- 
tories and  to  which  attention  may  be  briefly  called  here. 

Floors,  Walls  and  Ceilings. —  Stone,  brick,  concrete,  concrete- 
steel,  according  to  availability,  are  satisfactory  materials  of  which  to 
construct  a  condensery.  Intersecting  walls  or  partitions  are  best 
constructed  of  similar  material.  If  constructed  of  wood,  they  should 
rest  on  concrete,  brick  or  stone,  built  up  at  least  two  feet  from  the 
floor,  or  the  lower  two  feet  of  which  partitions  should  be  wains- 
coated  with  an  approved  quality  of  cement  plaster. 

All  floors  of  the  main  building  should  be  of  cement,  great  care 
being  taken  that  the  foundation  of  these  floors  be  of  uniformly 
hard  material,  thoroughly  tamped  and  avoiding  soft  spots.  The 
concrete  bed  should  be  at  least  four  inches  in  depth,  consisting  of 
one  part  of  cement,  two  parts  of  sand  and  four  parts  of  gravel. 
The  sand  should  be  sharp  building  sand  and  the  gravel  should  be 
washed  pebbles,  ranging  in  size  from  one-half  to  one  inch.  The 
top  dressing  should  be  not  less  than  one  inch  thick,  consisting  of  one 
part  of  cement  and  one  and  one-half  parts  of  sharp  building  sand. 
It  should  be  carried  up  on  the  walls  and  partitions  at  least  two 
inches,  forming  a  sanitary  cove.  After  finishing,  the  floors  should 
be  allowed  to  harden  for  at  least  two  weeks.  This  will  greatly  pro- 
long their  life.  It  is  advisable  to  use  some  cement  hardener  such 
as  Master  Builders'  cement,  or  Lapidolith,  etc.,  which  will  help  to 
make  these  floors  more  nearly  wear-,  water-,  dust-  and  crack-proof. 
It  is  difficult  to  keep  the  condensery  in  sanitary  condition  and  to 
protect  the  product  against  contamination,  unless  the  floors  of  the 
factory  are  and  stay  free  from  cracks  and  holes. 

Ventilation. —  A  proper  and  effective  system  of  ventilation  is 
another  very  important  and  too  often  entirely  neglected  factor  in 
the  planning  of  the  condensed  milk  factory.  This  applies  to  all 
parts  of  the  plant  where  work  is  being  done,  but  it  is  especially 
essential  in  rooms  where  free  steam  escapes.  The  ventilating  sys- 


34  BUILDING  AND  EQUIPMENT 

tern  should  be  adequate  to  afford  ready  and  quick  escape  of  steam, 
to  remove  foul  air  and  to  facilitate  the  regulation  of  temperature. 
Unless  free  steam  does  promptly  find  an  exit  from  the  factory 
rooms,  it  condenses  on  the  walls  and  ceilings,  making  them  sweat 
profusely,  causing  corrosion  of  the  walls  and  ceiling,  deterioration 
of  motors  and  other  similar  equipment,  and  molding  of  supplies; 
this  is  especially  the  case  during  the  winter  months.  The  removal 
of  foul  air  and  the  control  of  the  temperature  of  the  air  are  essen- 
tial for  the  comfort,  health  and  efficiency  of  the  employes. 

The  system  of  ventilation  that  will  accomplish  efficient  ventila- 
tion will  of  necessity  vary  with  the  type  of  plant  and  arrangement 
of  equipment.  Gravity  ventilation,  such  as  is  represented  by  the 
King  system  is,  under  average  conditions,  inadequate  to  produce 
satisfactory  results  in  factories,  like  milk  condenseries,  where  there 
is  bound  to  be  much  escape  of  free  steam.  The  exchange  of  air  is 
not  rapid  enough  to  remove  the  steam  before  it  condenses  on  the 
walls  and  ceilings,  especially  in  cold  weather.  It  is,  therefore,  ad- 
visable to  provide  for  some  form  of  forced  ventilation.  Under  cer- 
tain conditions  of  construction  an  air  flue  connecting  with  the  smoke 
stack  may  furnish  all  the  ventilation  needed.1  Under  many  other 
conditions,  however,  it  is  necessary  to  hood  that  equipment  from 
which  free  steam  escapes  in  large  volume,  such  as  can  washers,  and 
can  sterilizers,  hot  wells,  etc.,  and  to  draw  the  steam  away  through 
ducts  of  adequate  size  by  one  or  more  motor  fans  located  in  the 
outside  wall  or  ceiling. 

Drainage. — All  floors  of  the  manufacturing  rooms  should 
slope  to  facilitate  rapid  drainage.  A  fall  of  one-eighth  inch  per 
foot  is  usually  sufficient.  Large  water-sealed  floor  drains  should  be 
sufficiently  numerous  and  well  placed  in  all  rooms  to  rapidly  carry 
off  water.  The  surface  of  these  floor  drains  should  be  about  one- 
half  inch  below  that  of  the  adjoining  floor,  so  as  to  catch  the  water 
readily.  In  the  larger  rooms  open  drain-ditches  in  the  cement  floor, 
six  to  eight  inches  wide  and  covered  with  perforated  iron  plates,  are 
preferable  to  bell-traps.  They  may  be  placed  along  the  walls  or 
elsewhere.  They  should  be  not.  more  than  forty  feet  apart  and  have 
a  fall  of  one-eighth  inch  to  the  foot,  with  the  floor  sloping  toward 
them.  It  is  generally  most  convenient  to  have  all  the  drain  pipes 
enter  into  one  large  sewer  pipe  not  less  than  ten  inches  in  diameter, 

1  In  this  case  there  should  be  an  inner  and  outer  stack  with   an  air  space 
between  which  connects  with  the  air  flue. 


AND  EQUIPMENT  35 

for  a  condensery  receiving  about  fifty  thousand  pounds  of  milk 
daily,  which  should  dispose  of  all  the  factory  sewerage.  It  is  advis- 
able to  place  the  main  sewer  pipe  outside  the  building  and  to  have 
it  terminate  in  a  "clean-out."  This  will  afford  more  ready  access 
in  case  the  sewer  is  stopped  up. 

General  Plan  of  Factory. — Most  of  the  condensing  factories 
are  either  one-  or  two-story  buildings.  In  the  case  of  two-story 
buildings  the  first  floor  is  usually  devoted  to  the  boiler  and  engine 
rooms,  vat  room,  well  room,  filling,  sealing  and  packing  rooms.  On 
the  second  floor  are  installed  the  pan  room,  store  room  for  sugar 
and  box  shooks,  the  tinshop  and  possibly  the  offices.  A  basement  is 
sometimes  provided  and  used  for  the  storing  of  condensed  milk. 

Fig.  6  illustrates  a  floor  plan  of  a  milk  condensing  factory  with 
a  capacity  of  fifty  thousand  pounds  of  milk  daily.  All  operating 
rooms  are  located  on  one  floor.  The  arrangement  of  machinery 
permits  of  the  handling  of  the  milk  on  the  gravity  plan  or 'with 
pumps,  according  to  the  topography  of  the  site  and  the  elevation  of 
the  rooms.  The  receiving  room  floor  and  the  platform  which  ac- 
commodates the  vacuum  pans,  should  be  seven  to  eight  feet  above 
the  main  floor.  In  order  to  take  care  of  storage  of  water,  sugar,  tin 
cans,  barrels  and  box  shooks,  there  should  be  a  second  floor  over 
the  well  room  and  the  filling,  sealing  and  sterilizing  room.  The 
ceiling  of  these  rooms  should  be  not  less  than  sixteen  feet  above 
the  floor. 

The  rooms  are  so  arranged  as  to  necessitate  the  minimum  ex- 
penditure of  machinery,  conveyors  and  labor.  All  work  rooms 
open  on  the  railway  switch,  and  the  storage  room  is  accessible  by 
two  elevators.  The  well  room,  where  most  of  the  steam  is  needed, 
is  next  to  the  boiler  room,  so  as  to  minimize  condensation  in  the 
steam  pipes.  If  the  main  steam  pipes  are  properly  insulated,  this 
arrangement  should  furnish  the  vacuum  pans  with  dry  steam.  The 
floor  in  the  boiler  room  should  be  two  feet  below  the  main  floor,  in 
order  to  give  additional  fall  for  the  condensation  water  from  jacket 
and  coils  of  the  vacuum  pans  to  the  boiler  feed  tank. 

The  partition  between  the  receiving  room  and  testing  room  is 
equipped  with  a  cabinet,  opening  on  both  sides  so  that  the  sample 
bottles  can  be  placed  on  the  shelves  in  the  receiving  room  and  taken 
off  the  shelves  in  the  test  room. 


36  BuiivDiNG  AND  EQUIPMENT 

From  the  weigh  cans  on  the  receiving  platform  the  milk  runs 
direct  into  the  hot  wells,  which  are  sufficient  in  number  to  con- 
veniently divide  the  milk  into  batches  and  to  heat  the  milk  with  the 
least  possible  delay.  The  capacity  of  the  vacuum  pumps  is  aug- 
mented by  their  close  proximity  to  the  vacuum  pans  and  the  hot- 
wells  and  by  the  fact  that  the  water  supply  tanks  are  overhead. 
The  space  to  be  evacuated  is  confined  very  largely  to  the  vacuum 
pan  only,  the  milk  has  to  be  lifted  by  the  vacuum  pump  but  a  few 
feet  and  the  water  runs  into  the  condenser  by  gravity. 

From  the  well  room  the  condensed  milk  is  transferred  to  the 
tanks  on  the  platform  over  the  filling  machines.  The  evaporated 
milk  is  pumped  from  the  cooling  coils  through  the  wall  and  the 
sweetened  condensed  milk  is  raised  to  the  platform  in  ten-gallon 
cans  on  the  elevator,  or  is  forced  by  a  piston  pump  into  the  tanks 
feeding  the  filling  machines.  The  sealing  benches  are  equipped 
with  "self-heating  soldering  coppers.  In  the  place  of  the  soldering 
benches  and  hand  coppers,  automatic  sealing  machines  may  be  in- 
stalled. The  sterilizers  and  shakers  are  conveniently  placed  to  take 
care  of  the  sealed  evaporated  milk.  The  tin  cans  for  the  sealing 
room  and  the  box  shooks  for  the  packing  room  are  brought  down 
from  the  storage  room  overhead  on  the  elevator.  The  labeling  and 
packing  room,  equipped  with  the  labeling  and  box  nailing  machines, 
provides  for  considerable  storage  of  the  finished  product.  Addi- 
tional storage  at  a  moderate  and  uniform  temperature  might  be 
provided  for  by  a  basement  under  the  packing  room.  A  label  stock 
room  furnishes  satisfactory  storage  for  the  labels. 

In  case  the  factory  manufactures  its  own  tin  cans,  a  tinshop, 
equipped  with  the  necessary  machinery  (see  list  of  machinery  and 
equipment)  should  be  located  in  as  close  and  convenient  proximity 
to  the  filling  and  sealing  room  as  possible.  A  suitable  place  is  di- 
rectly opposite  the  filling  room  with  the  railway  track  separating 
the  latter  from  the  tinshop.  The  tinshop  should  have  two  outside 
doors,  opening  out  on  the  track,  and  its  machinery  should  be  so  ar- 
ranged that  the  tin  plate  can  be  unloaded  from  the  car  at  one  door, 
is  moved  back  through  the  machinery  and  appears  again  in  the 
form  of  finished  cans  at  the  other  door,  directly  opposite  the  filling 
room  and  ready  for  the  reception  of  the  condensed  milk.  Instead 
of  erecting  a  separate  building  for  the  tinshop,  the  latter  may  also 


AND  EQUIPMENT  37 

be  conveniently  installed  in  the  second  story  directly  over  the  fill- 
ing room. 

Where  natural  gas  and  gas  from  municipal  corporations  is 
not  available,  one  or  more  gasoline  gas  generators  should  be  in- 
stalled. These  gas  generators  contain  inflammable,  material  and 
should,  therefore,  be  located  at  a  reasonable  distance  from  the  main 
building. 

List  of  Equipment. — The  following  is  a  list  of  the  principal 
machinery  and  equipment  needed  in  an  up-to-date  condensery  with 
a  capacity  of  fifty  thousand  pounds  of  milk  daily : 

BOILER    BOOM 

Boilers  with  a  total  capacity  of  400  H.  P. 
1  boiler  feed  tank. 
1  boiler  feed  pump. 
1  boiler  water  heater. 

ENGINE     ROOM' 

1  40  H.  P.  engine. 

2  well  pumps,  150  gallons  per  minute  each. 

1  80  light  dynamo. 

Pipe  and  thread-cutting  tools,  anvil  and  forge. 

RECEIVING    BOOM 

2  1000-pound  weigh  cans,  "low  down"  style. 
2  6-beam  milk  scales. 

1  can-washing  machine  with  steam  and  water  jets  and 

air  blower  for  drying  the  cans. 
1  milk  sample  bottle  rack. 

WELL    BOOM 

6  5000-pound  capacity  jacketed  kettles  with  revolving 

agitators  and  superheating  device. 
1  6-foot  vacuum  pan. 

1  7-foot  vacuum  pan. 

2  vacuum  pumps. 

2  500-gallon  standardizing  vats. 
1  6-cylinder  homogenizer. 

1  internal  tube  cooler,  capacity  5000  to  8000  pounds  per 
hour,  for  cooling  evaporated  milk. 

1  In  case  municipally  generated  electricity  is  available,  there  is  no  need  of  a 
Dynamo  and  much  of  the  equipment  may  be  supplied  with  direct  drive  by  motors. 
This  would  obviate  the  installation  of  a  steam  engine. 


38  BUILDING  AND  EQUIPMENT 

2  36-can  cooling  vats  with  cans,  cross  bars  and  paddles, 

complete,  or 
2  5000-lbs.  circular  cooling  vats  with  vertical  coils  for 

cooling  sweetened  condensed  milk. 
1  wash  tank. 
1  elevator. 
1  sugar  chute. 
1  2-beam  platform  scale. 

1  truck. 

FILLING,    SEALING    AND    STERILIZING    BOOM 

4  200-gallon  condensed  and  evaporated  milk  vats. 

2  filling  machines  for  sweetened  condensed  milk. 
2  filling  machines  for  evaporated  milk. 

4  soldering  benches,  5x20  feet,  with  10  self-heating  sol- 
dering coppers  each,  or 

1  or  more  sealing  machines  with  can-testing  baths,  the 

number  depending  on  type  and  capacity  of  machine 
used. 
2000  wooden  trays  holding  24  16-ounce  cans  each. 

2  sterilizers,  capacity  75  to   100  cases  each,  complete 

with  iron  trays. 

1  double  shaker. 

2  trucks. 

LABELING  AND  PACKING  BOOM 

2  labeling  machines. 
2  nailing  machines. 
2  trucks. 

TESTING   BOOM 

2  24-bottle  Babcock  testers,  with  one  gross  of  standard 
milk  test  bottles  and  accessories,  complete. 

Equipment  for  chemical  and  bacteriological  analyses  of 
milk,  milk  products  and  sugar. 

OFFICES 

Usual  equipment. 

TOILET    BOOMS 

Usual  equipment. 


BUILDING  AND  EQUIPMENT  39 

OVERHEAD  STORAGE  ROOM 

1   50-000-gallon  water  tank.    This  tank  is  preferably  lo- 
cated outside  of  factory. 
1  4-beam  platform  scale  for  sugar. 

ADDITIONAL    EQUIPMENT 

1  gasoline  gas  generator  (complete),  needed  in  absence 
of  access  to  natural  gas  or  municipal  gas. 

1  15-ton  ammonia  compressor,  with  ammonia  and  brine 

pipe  lines,  circulating  pump  and  brine  tank. 

2  15,000-lbs.  jacketed  circular  tanks  for  refrigeration 

of  stored  evaporated  milk. 

TIN  SHOP 

Needed  in  case  cans  are  manufactured  at  the  factory. 
2  squaring  shears. 
2  body  cutting  machines. 
2  lock  seamers. 
6  presses. 

2  crimping  machines. 
2  soldering  floats. 
1  can  tester  with  vacuum  pump. 
1  can  wiper. 
1  lathe  with  tools. 
1  gasoline  gas  generator,  complete. 
1  25  H.  P.  engine  or  motor. 
200  can  crates. 

Economic  Arrangement  of  Machinery.— In  the  arrangement 
and  connection  of  the  machinery,  economy  of  manufacture  and 
sanitation  of  the  product  should  receive  serious  consideration.  The 
machinery  should  be  so  arranged  as  to  reduce  to  the  minimum  the 
space,  pumps,  pipes  and  conveyors  needed.  Pumps,  conveyors, 
pipes  and  fittings  are  expensive,  and  the  space  saved  by  judicious 
arrangement  of  the  stationary  machinery  may  be  used  to  advantage 
for  other  purposes. 

Human  muscle  is  the  most  expensive  form  of  motive  power. 
Wherever  muscle  can  be  replaced  by  machinery  and  where,  by  in- 
telligent arrangement  of  the  machinery,  unnecessary  steps  and  hand- 
ling can  be  avoided,  the  cost  of  manufacture  is  reduced. 


40  BUILDING  AND  EQUIPMENT 

The  matter  of  insulation  of  ammonia,  brine,  steam  and  water 
pipes  is  an  important  item  as  related  to  the  economy  of  fuel.  For 
proper  and  economical  insulation  the  following  types  of  pipe  cover- 
ing are  recommended: 

Ammonia  and  Brine  Lines. — 

1st    layer  of  tarred  felt. 

2nd  layer  of  1"  thick  hair  felt. 

3rd  layer  of  tarred  felt. 

4th  layer  of  1"  thick  hair  felt. 

5th  layer  of  tarred  felt. 

6th  layer  of  wove-felt  paper. 

7th  layer  of  8-oz.  canvas  jacket,  sewed  on. 

8th  layer  of  sizing  and  one  coat  of  lead  and  oil  paint. 

Each  layer  of  hair  felt  must  be  securely  wound  with  twine. 
Each  layer  of  all  material  should  be  coated  with  hot  asphalt,  ap- 
plied while  hot,  excepting  layers,  6,  7  and  8. 

Special  seals  must  be  made  at  all  flanges  and  fittings,  and  such 
flanges  and  fittings  must  be  insulated  independently.  This  arrange- 
ment will  prevent  damage  to  adjoining  coverings,  should  fittings 
spring  leaks. 

Before  applying  pitch  or  asphalt,  the  necessary  precautions  must 
be  taken  to  have  the  pipes  thoroughly  dry  and  the  asphalt  or  pitch 
must  be  hot. 

Steam  Lines. — Air  cell  asbestos  covering,  or  covering  of  equal 
insulating  and  lasting  quality,  one  inch  thick  on  pipes,  and  fittings 
to  be  built  up  of  asbestos  cement  to  a  corresponding  thickness; 
smoothly  finished  and  neatly  canvassed,  with  metal  bands  at  18" 
intervals.  Before  putting  on  the  metal  bands  the  covering  should 
receive  two  coats  of  asbestos  cold  water  paint. 

Cold  Water  Lines. — Covering  of  wool  felt,  tar  paper  lined, 
sectional,  one  inch  thick  on  pipes ;  fittings  to  be  built  up  to  a  corre- 
sponding thickness  with  one  inch  hair  felt,  the  entire  line  should  be 
neatly  finished  with  a  graded  mixture  of  Portland  cement  and 
asbestos  cement,  and  canvas-jacketed  and  equipped  with  metal  bands 
at  18" 'intervals.  Before  putting  on  the  metal  bands,  the  covering 
should  receive  two  coats  of  asbestos  cold  water  paint. 


SUPPLY  41 


Sanitary  Arrangement  of  Machinery.  —  Milk  pumps,  milk 
pipes,  milk  troughs  and  other  milk  conveyors  are,  at  best,  enemies 
of  sanitation.  They  should  be  avoided  wherever  possible.  The 
gravity  system  of  conveying  milk  should  be  used  in  preference  to 
the  pumping  system.  Milk  pipes  should  be  short  and  accessible; 
all  vats  should  be  of  sanitary  construction;  wooden  jackets  should 
not  be  tolerated;  all  seams  in  the  vats  and  kettles  should  be  well 
flushed  with  solder  ;  milk  pumps  should  be  brass  lined  ;  all  milk  pipes 
should  be  of  black  iron  pipe  made  smooth  on  the  inside  by  sand- 
blasting, or  of  galvanized  iron  or  copper,  heavily  tinned  over  on 
the  inside  ;  long  lines  of  milk  pipes  should  be  equipped  with  unions 
at  short  distances;  crosses  or  sanitary  couplings  should  be  used  in 
place  of  elbows,  in  order  to  render  all  sections  of  the  milk  pipes 
easily  accessible  to  flue  brushes. 


CHAPTER  III. 
MILK  SUPPLY 

Basis  of  Buying  Milk.—  The  prices  which  the  condensery  pays 
the  patrons  are  not  usually  governed  by  any  board  of  trade.  They 
do  not  even  necessarily  follow  the  quotations  of  the  butter  and 
cheese  market.  They  are  generally  announced  from  three  to  six 
months  in  advance.  They  average,  in  most  cases,  from  twenty  to 
fifty  cents  higher  per  hundred  pounds  of  milk  than  those  paid  by 
the  creameries  and  cheese  factories. 

The  milk  condenseries,  as  a  whole,  have  been  slow  in  adopting 
the  butter  fat  content  of  milk  as  their  basis  for  payment.  Even  up 
to  a  few  years  ago  most  condenseries  were  paying  for  the  milk  on 
the  one  hundred  weight  basis  and  some  factories  were  still  clinging 
to  the  mediaeval  custom  of  buying  milk  by  the  quart,  using  the 
yardstick  for  remnant  cans.  Other  factories  paid  a  stated  price  per 
hundred  weight  for  all  milk  testing  say  4  per  cent  fat  and  over  and 
made  corresponding  reductions  for  milk  containing  less  than  4  per 
cent  fat.  Still  others  paid  a  premium  for  milk  testing  above  4  per 
cent  fat.  A  few  concerns  only  bought  milk  on  the  straight  butterfat 
basis. 


42  MII.K  SUPPLY 

As  far  as  the  condensery  is  concerned  it  is  entirely  feasible  to 
pay  for  all  milk  strictly  on  the  butter  fat  basis.  Milk  rich  in  fat, 
and  therefore  rich  in  solids,  yields  more  condensed  milk  than  milk 
poor  in  fat.  To  pay  by  the  hundred  weight,  regardless  of  quality  is 
a  practice  which  discriminates  in  favor  of  breeds  of  low-testing  milk 
and  against  breeds  of  high-testing  milk.  This  practice  has,  in  fact, 
had  the  result  that  in  the  milk  supply  territory  of  these  condenseries 
the  breeds  and  individuals  of  cows  producing  low-testing  milk  were 
encouraged  and  developed  until  they  largely  predominated,  at  the 
expense  of  breeds  of  cows  producing  high-testing  milk.  This  situa- 
tion in  turn  was  responsible  for  the  popular,  though  erroneous 
impression,  that  milk  from  the  Holstein,  Ayrshire  and  Brown  Swiss 
breeds  is  better  suited  for  milk  condensing  purposes  than  milk  from 
the  Channel  Island  breeds. 

Within  the  last  half  decade,  during  which  the  condensed  milk 
industry  has  experienced  so  great  a  development,  the  great  majority 
of  condenseries  have  abandoned  their  old  way  of  paying  for  milk 
by  volume,  or  weight  only.  Many  condensing  concerns  are  now 
buying  their  milk  on  the  straight  butter  fat  basis  and  nearly  all  of 
the  other  condenseries  pay  for  their  milk  on  the  basis  of  a  standard 
fat  content,  penalizing  the  farmer  by  lower  prices  for  milk  that  falls 
below  a  specified  per  cent  of  fat,  and  giving  him  a  bonus  for  milk 
in  which  the  per  cent  of  fat  is  over  the  standard  figure  specified. 

The  great  bulk  of  the  milk  supply  reaches  the  condensery  by 
wagon  or  by  motor  truck.  Usually  part  of  the  cost  of  transportation 
is  borne  by  the  factory  and  part  by  the  farmer.  Shipments  by  rail 
are  rare,  the  uncertainty  of  rail  transportation,  with  its  frequent 
delays,  jeopardizes  the  quality  of  the  milk.  Payments  for  the  milk 
are  generally  made  monthly. 

Quality. —  The  quality  of  the  fresh  milk  is  the  first  and  most 
important  factor  to  be  considered.  The  milk  condensing  factory, 
ignoring  this  fact  and  accepting  milk  from  unsanitary  dairies  and 
careless  dairymen,  is  bound  to  pay  the  penalty  for  such  neglect 
sooner  or  later. 

Polluted  milk  and  milk  that  has  not  been  cooled  promptly  and 
to  a  reasonably  low  temperature  on  the  farm,  may  pass  through  the 
process  successfully,  if  it  is  not  too  sour.  The  condensed  milk  made 
from  it,  though,  is  inferior  in  flavor  and  keeping  quality,  and  usually 


MILK  SUPPLY  43 

shows  signs  of  deterioration  and  decay  before  it  reaches  the  con- 
sumer. The  risk  of  handling  such  milk  is  very  great ;  it  may  result 
in  total  loss  to  the  manufacturer.  The  trouble  may  and  often  does 
begin  before  the  process  is  completed.  Unclean,  abnormal,  or  partly 
fermented  milk,  when  subjected  to  the  process,  is  prone  to  curdle 
and  whey  off;  the  condensed  milk  becomes  lumpy  and  shows  other 
defects.  This  is  especially  true  where  superheating  is  practiced  and 
where  evaporated  milk  is  made. 

Milk  that  has  received  the  best  of  care  on  the  farm  may  be 
detrimental  to  the  interests  of  the  condensery,  if  it  comes  from 
cows  less  than  thirty  days  before  their  parturition,  or  from  fresh 
cows  within  the  first  seven  days  after  calving,  or  from  cows  other- 
wise in  abnormal  condition.  Such  milk  is  often  abnormal  in  its 
chemical  properties,  and,  when  subjected  to  high  temperatures, 
undergoes  changes  that  make  its  manufacture  into  a  marketable 
condensed  milk  difficult. 

Control  of  Quality — Every  well  managed  milk  condensing  fac- 
tory plays  the  part  of  an  educator  in  the  production  of  sanitary 
milk.  The  condensery.  usually  issues  a  set  of  rules,  setting  forth 
specifically  the  conditions  under  which  the  milk  coming  to  the  fac- 
tory shall,  or  shall  not  be  produced.  Copies  of  these  rules,  which  are 
generally  a  part  of  the  contract,  are  placed  in  the  hands  of  all 
patrons.  The  condensery  employs  one  or  more  dairy  inspectors 
whose  business  it  is  to  see  that  the  rules  are  rigidly  enforced.  These 
rules  cover,  in  general,  the  following  principal  points : 

1.  Cows. — The  milk  must  come   from  healthy  cows.     Milk 
from  cows  that  are  diseased,  or  that  have  a  diseased  udder,  or  that 
are  otherwise  in  poor  physical  condition,  will  be  rejected. 

2.  FEED  AND  WATER. — Do  not  feed  weeds,  roots,  or  other  feed 
stuffs  possessing  strong  and  obnoxious  odors,  such  as  onions,  garlic, 
turnips,  cabbage,  wet  distillery  slops,  decayed,  musty  or  sour  silage, 
or  other  fermented  feed.     (Some  condenseries  prohibit  the  use  of 
all  silage.     This  restriction  betrays  prejudice  and  ignorance  on  the 
part  of  the  management  concerning  the  great  value  and  absolute 
harmlessness  of  good  silage  as  a  dairy  feed.     It  is  an  injury  to  the 
dairy  interests  of  the  country.     Corn  silage  or  other  silage,  in  good 
condition,  and  fed  in  reasonable  quantities,  does  in  no  way  injure 
the  milk  for  condensing  purposes.)     The  cows  must  be  supplied 
with  clean,  fresh  water. 


44  MILK  SUPPLY 

•  i 

3.  LACTATION  PERIOD. — Reject  all  milk  from  cows  less  than 
thirty  days  before,  and  of  the  first  seven  days  after  calving.  • 

4.  MILKERS  AND  MILKING. — Milk  with  clean,  dry  hands  into 
clean  utensils  and  remove  the  milk  to  the  milk  room  immediately 
after  drawn. 

5.  STRAINING. — Strain  the  milk  in  the  milk  room  through  a 
fine  wire  mesh  strainer  (80  to  100  meshes  to  the  inch).    Do  not  use 
cloth  strainers. 

6.  COOLING. — Cool  the  milk  to  60  degrees  F.  or  below  and 
keep  it  at  that  temperature  until  it  reaches  the  factory.    Do  not  mix 
the   warm   morning's   milk   with   the   cold   night's    milk;    cool   the 
morning's  milk  before  mixing,  or  send  it  to  the  factory  in  separate 
cans. 

7.  CARE  OF  UTENSILS. — Rinse   with   cold  water,   wash  with 
warm  water  and  washing  powder,  and  rinse  with  boiling  water  all 
milk  utensils  thoroughly  after  use ;  keep  them  in  a  clean  place  be- 
tween milkings.    Do  not  store  the  milk  on  the  farm  in  cans  that  have 
not  been  washed  by  the  factory. 

8.  STABLES. — Whitewash  the  stable  twice  every  year  and  re- 
move manure  daily.     (Some  condenseries  furnish  spray  pumps  for 
applying  whitewash.) 

Inspection  of  Milk  at  the  Condensery. —  At  the  condensery 
the  milk  is  subjected  to  rigid  inspection  by  a  man  who  is,  or  should 
be,  an  expert  on  milk  inspection ;  every  can  is  examined.  Warm  milk 
and  milk  that  is  tainted,  or  smells  slightly  sour  should  be  rejected. 

INSPECTION  OF  MILK  BY  SENSE  OF  SMELL  AND  TASTE. — In  most 
cases  the  milk  isa  inspected  with  reference  to  odor.  The  inspector 
quickly  raises  the  cover  of  each  can  to  his  nostrils.  The  odor  in 
the  cover  is  typical  of  that  in  the  can.  If  it  is  "off,"  the  can  is 
rejected.  An  experienced  man  on  the  platform  can,  by  the  use  of 
this  method,  tell  with  much  accuracy,  whether  the  milk  should  pass 
or  not. 

INSPECTION  OF  MILK  ACCORDING  TO  ITS  TEMPERATURE. — The 
temperature  is  also  noted.  This  need  not  be  done  with  the  ther- 
mometer in  each  case.  By  placing  his  hand  on  the  body  of  the  can, 
or  by  noting  the  warmth  of  the  air  and  odor  in  the  cover  immediately 
after  removing  it,  or  by  the  presence  or  absence  of  small  particles 


MILK  SUPPLY  45 

of  butter  floating  on  the  surface  of  the  milk,  the  inspector  can 
readily  tell  if  the  milk  has  or  has  not  been  properly  cooled.  A  correct 
thermometer  should  always  be  on  the  platform  for  guidance. 

INSPECTION  OF  MILK  BY  THE:  USE:  OF  ACID  TE:STS. — Since  the 
degree  of  acidity,  or  the  sweetness  of  the  milk,  is  one  of  the  chief 
factors  that  determines  its  fitness  for  condensing  purposes,  tests 
that  rapidly  and  accurately  determine  the  per  cent  of  lactic  acid  in 
the  fresh  milk,  are  of  great  service. 

Some  concerns  have  adopted  a  definite  acid  standard  of  milk, 
rejecting  all  milk  containing  more  than  the  maximum  per  cent  of  acid 
of  their  standard,  and  they  test  every  can  of  milk  received  with  an 
acid  test.  This  method  insures  sweet  milk  in  the  factory,  provided 
that  the  alkaline  solutions  used  are  correct.  This  work  involves 
considerable  expense,  however,  and  unless  the  solution  is  carefully 
prepared  and  made  up  fresh  often,  its  use  may  yield  misleading 
results.  Again,  when  the  acid  test  is  performed  on  the  milk  of  each 
can,  the  acceptance  or  rejection  of  the  milk  depends  altogether  on 
the  per  cent  of  acid  it  contains.  Although  milk  may  be  otherwise 
unfit  for  use,  it  will  pass,  as  long  as  it  is  low  in  acidity.  Experience 
has  shown  that,  while  it  is  necessary  for  the  condensery  to  decide 
on  a  maximum  acidity  of  milk  above  which  all  milk  be  rejected, 
the  nose  and  the  palate  of  the  experienced  inspector  are  better 
criterions  than  the  acid  test  alone,  as  to  the  fitness  of  milk  for  con- 
densing. Acid  tests  are  valuable  in  the  case  of  uncertainty  and 
suspicion  as  to  the  quality  of  any  given  can  of  milk.  All  milk  con- 
taining .2  per  cent  lactic  acid  or  more  is  dangerous  for  condensing 
purposes  and  should  be  rejected. 

Acid  Test  for  Daily  Use,  Where  Bach  Can  of  Milk  is  Tested. — 
Stock  Solution. — Weigh  out  two  hundred  grams  of  sodium  hydrate 
C.  P.  and  add  distilled  water  to  make  up  one  liter.  Keep  tightly 
stoppered. 

Solution  for  Daily  Use. — Mix  4  c.c.  of  stock  solution  with  991 
c.c.  of  distilled  water,  and  add  5  c.c.  of  phenolphthalein  indicator. 
The  indicator  is  prepared  as  follows :  dissolve  one  gram  of  dry 
phenolphthalein  in  100  c.c.  of  50  per  cent  alcohol.  Each  cubic 
centimeter  of  the  prepared  alkaline  solution  neutralizes  .01  per  cent 
lactic  acid,  20  c.c.  of  the  prepared  solution,  therefore,  neutralize  .2 
per  cent  lactic  acid,  when  a  17.6  c.c.  pipette  is  used  for  measuring 
out  the  milk. 


46  MILK  SUPPLY 

Making  the  Test. — With  the  Babcock  pipette,  measure  17.6  c.c. 
into  a  white  cup.  With  a  small  dipper,  holding  exactly  20  c.c.,  pour 
20  c.c.  of  the  prepared  solution  into  the  cup;  stir  or  shake.  If  the 
mixture  remains  faintly  pink,  it  contains  less  than  .2  per  cent  acid 
and  will  pass ;  if  it  turns  white,  it  contains  more  than  .2  per  cent 
acid  and  should  be  rejected. 

The  stock  solution  should  be  standardized  by  a  chemist.  The 
prepared  solution  should  be  made  up  daily.  Both  solutions  should 
be  kept  in  glass  bottles,  tightly  corked.  The  bottle  containing  the 
stock  solution  should  be  glass-stoppered. 

Acid  Test  for  Use  on  Suspicious  Cans  Only. — The  Farrington 
Alkaline  Tablet  Test.  Use  an  eight  ounce,  wide-mouth  bottle,  place 
in  it  sixteen  Farrington  alkaline  tablets,  add  eight  ounces  of  distilled 
water  or  rain  water,  or  any  pure  water  relatively  free  from  car- 
bonates. Stopper  tightly  and  let  stand  for  six  hours,  or  until  the 
tablets  are  completely  dissolved.  This  solution  neutralizes  .2  per 
cent  of  lactic  acid  in  equal  parts  of  milk. 

Making  the  Test. — Use  small  dippers  of  the  same  size  for  milk 
and  for  test  solution.  Pour  into  a  white  cup  one  dipperful  of  milk 
and  one  dipperful  of  solution.  If  the  mixture  turns  white,  it  con- 
tains more  than  .2  per  cent  lactic  acid  and  should  be  rejected.  If  it 
remains  pink,  the  milk  contains  less  than  .2  per  cent  acid. 

THE  BOILING  TEST. — Inspection  by  Heating.  The  heating  to 
the  boiling  point  of  samples  of  suspicious  milk  furnishes  a  most 
reliable  means  to  determine  the  fitness  of  such  milk  for  condensing. 
In  many  instances  milk  may  satisfactorily  pass  the  other  tests  and 
yet  it  may  not  be  in  condition  to  stand  the  heat  to  which  it  will  be 
subjected  in  the  process.  If  it  curdles,  when  boiled,  it  is  obviously 
unfit  for  use.  This  test  shows  more  than  the  acid  test  above.  By 
its  use  the  operator  is  able  to  detect  milk  otherwise  abnormal,  such 
as  milk  containing  colostrum,  etc.,  or  the  proteids  of  which  are  un- 
stable for  other  reasons. 

Making  the  test. — The  boiling  test  is  simple  and  can  be  ma- 
nipulated rapidly.  A  sample  of  the  questionable  milk  is  taken  into 
a  small  dipper.  The  dipper  is  held  up  against  a  steam  jet  turned 
down  into  the  milk.  Direct  steam  is  turned  into  the  milk  until  it 
comes  to  a  boil.  If  flakes  or  specks  of  curd  cling  to  the  sides  of  the 
dipper,  the  milk  is  unfit  for  use. 


MILK  SUPPLY 


47 


An  alcohol  lamp  ar  gas  burner  on  the 
platform  may  be  used  for  heating  the  sample. 
In  this  case  a  few  cubic  centimeters  of  the 
milk  are  discharged  with  an  ordinary  pipette 
into  an  ordinary  test  tube,  such  as  are  in  com- 
mon use  in  the  chemical  laboratory  and  can 
be  obtained  from  the  drug  store.  The  tube 
is  held  over  the  flame  and  the  milk  comes  to 
a  boil  in  less  than  a  minute.  If  the  milk  is 
in  good  condition  the  sides  of  the  glass  tube 
remain  perfectly  clear.  If  it  curdles  upon 
heating,  the  sides  of  the  tube  show  fine  specks 
of  the  curd.  The  appearance  of  these  specks 
condemns  the  milk. 

THE:  SEDIMENT  TEST. — This  test  shows 
the  relative  amount  of  dirt  present  in  milk. 
One-half  pint  of  milk  is  passed  through  a 
small  circle  of  absorbent  cotton  and  the 

amount  of  mechanical  impurities  present  in  the  milk  is  indicated  by 
the  color  of  the  cotton  after  filtration.  In  order  to  hasten  the 
filtration,  the  milk  is  forced  through  the  filter  under  slight  pressure, 
this  is  accomplished  by  a  rubber  bulb  attachment  to  the  apparatus, 
as  shown  in  the  accompanying  Fig.  7. 


Fig.    7. 
The    sediment    tester 


Fig.    8.     Cotton    Filters 


Clean  milk 


Dirty  milk 


If  the  cotton  retains  a  white  or  creamy  color,  the  milk  is  rel- 
atively free  from  filth.  Milk  produced  under  unsanitary  conditions 
stains  the  cotton  brown  or  black. 


48 


MILK  SUPPLY 


These  cotton  filters  may  be  pasted  on  a  sheet  of  paper  similar 
to  a  milk  sheet,  arranged  so  that  the  circles  are  placed  opposite  the 
respective  patron's  name  or  number.  When  shown  to  the  patrons 
who  come  to  the  factory,  they  furnish  a  most  effective  object  lesson 
to  them.  When  the  milk  reaches  the  factory  on  route  wagons  or 
by  rail,  cards  similar  to  Figure  9  may  be  mailed  to  the  patrons. 
The  evidence  is  so  conclusive  that  even  the  most  obstinate  patron 
cannot  help  admitting  his  guilt  and  can  usually  be  induced  to 
"clean  up." 


.MILK  CONDENSING  COMPANY 
SEDIMENT  CARD 


NAME 


ADDRESS 


DATE 


No. 


THIS  IS  THE  AMOUNT  OF  DIRT  IN 
ONE  PINT  OF  YOUR  MILK 


Fig.  9. 

FERMENTATION  TESTS. — These  tests  are  of  great  value  in  the 
rapid  determination  of  the  kind  of  bacteria  with  which  the  milk 
from  individual  patrons  is  contaminated.  Glass  tubes  are  filled 
one-half  full  of  milk  from  each  patron.  These  tubes  are  set  in  a 
constant  water  bath  at  100  degrees  F.  and  the  changes  which  milk 
undergoes  are  noted  after  six,  twelve  and  twenty-four  hours. 

A  solid  curd  with  a  clear  whey  indicates  that  lactic  acid  bacteria 
are  the  chief  organisms  and  that  the  milk  has  been  produced  under 
cleanly  conditions.  These  organisms  are  killed  when  the  milk  is 
heated  in  the  hot  wells.  Such  milk  therefore  is  safe,  unless  it  con- 
tains excessive  acid,  as  shown  by  the  acid  test. 

A  curd  with  gas  holes,  or  that  which  is  torn  to  pieces  in  the 
tubes,  shows  the  presence  of  gas-producing  germs.  These  come 


FACTORY  SANITATION  49 

largely  from  manure  and  other  filth.  Among  these  are  Bacillus  coli 
communis,  the  natural  inhabitant  of  the  colon  of  the  animal,  and 
butyric  acid  organisms  which  are  spore  bearers.  The  latter  espe- 
cially may  give  rise  to  serious  milk  defects,  causing  "swell  heads." 
Patrons  sending  such  milk  should  be  looked  after  at  once. 

If  the  curd  dissolves,  or  no  curd  is  formed  and  the  milk 
changes  into  a  transparent  liquid,  it  usually  is  contaminated  by 
germs  from  the  dust  of  hay  and  bedding,  or  polluted  water.  To 
this  class  of  organisms  belong  Bacillus  subtilis,  Bacillus  fluorescens 
liquifaciens,  Plectridium  foetidum,  Bacillus  putrificus,  etc.  Some 
of  these  are  violent  gas  producers  and  most  of  them  are  spore-bear- 
ers. They  are  the  cause  of  some  of  the  most  disastrous  milk  defects. 
Dairies  from  which  such  milk  comes  should  be  vigorously  inspected 
and  all  milk  from  them  should  be  rejected,  until  the  patrons  have 
learned  how  to  furnish  sanitary  milk. 

Milk  that  remains  unchanged  for  twenty-four  hours  when  sub- 
jected to  the  fermentation  test,  suggests  that  it  contains  some  pre- 
servative. It  is  possible,  however,  for  milk  produced  under  ideally 
sanitary  conditions  to  remain  normal  and  unchanged  even  at  these 
high  temperatures  for  several  days.  Where  milk  comes  to  the  fac- 
tory in  bulk  as  is  the  case  in  the  condensery,  samples  showing  ab- 
normal keeping  quality  should  be  regarded  with  suspicion,  and  the 
respective  dairies  should  receive  immediate  and  thorough  inspection. 

TESTS  FOR  BUTTERFAT  AND  SPECIFIC  GRAVITY. — In  the  factories 
where  the  milk  is  not  paid  for  on  the  butter  fat  basis,  composite 
samples  should  be  taken  daily,  to  be  tested  for  fat  and  specific 
gravity,  at  regular  intervals  of  from  two  to  four  weeks,  in  order 
to  detect  possible  adulterations  by  skimming  or  by  the  addition  of 
water.  For  specific  directions  for  the  Babcock  test,  the  use  of  the 
lactometer  and  tests  for  preservatives  see  Chapter  XXXI  "Chem- 
ical Tests  and  Analyses  of  Milk  and  Milk  Products"  and  Chapter 
XXXIII  "Detection  of  Adulterants  and  Preservatives,  Etc," 

FACTORY  SANITATION 

In  the  previous  paragraphs,  special  emphasis  was  placed  on  the 
great  importance  of  a  good  quality  of  fresh  milk.  It  is  equally 
essential  that  the  factory  be  kept  in  exemplary  condition  as  to  clean- 
liness and  sanitation.  This  is  necessary  because  of  its  effect  on  the 


50  FACTORY  SANITATION 

patrons  and  on  the  wholesomeness  and  marketable  property  of  the 
finished  product. 

Effect  on  Patrons. —  It  does  not  take  the  watchful  eye  of  the 
intelligent  patron,  who  daily  comes  to  the  factory,  very  long  to  learn, 
whether  the  manufacturer  gives  his  milk  as  good  care  as  he  gave 
it  on  the  farm.  A  good  example  set  by  the  factory  will  mean  much 
toward  instilling  the  patron  with  ambition  to  do  likewise  on  the 
farm.  Shiftlessness  is  a  contagious  disease,  to  which  the  average 
farmer  is  very  susceptible.  It  is,  therefore,  inconsistent  for  the 
factory  to  issue  and  enforce  rules  of  sanitation  for  the  dairy  farmer 
when,  within  its  own  walls,  all  principles  of  sanitation  are  violated. 

Effect  on  Wholesomeness  of  the  Product.— Uncleanliness  and 
filth  interfere  with  the  wholesomeness  of  the  product.  Condensed 
milk  made  in  a  factory  ignoring  sanitation,  may  contain  certain 
products  of  decay  which  are  poisonous  to  the  human  system.  Again, 
it  may  contain  germs  of  infectious  diseases  and  thus  become  the 
cause  of  widespread  epidemics  of  these  diseases  and  possibly  claim 
many  victims.  ^As  a  matter  of  common  decency  and  of  duty  to  the 
commonwealth,  the  condensery  should  pay  close  attention  to  clean- 
liness in  all  operations. 

Effect  on  the  Marketable  Property  of  the  Product. — Again, 
uncleanliness  in  the  factory  is  bound  to  bring  financially  disastrous 
results.  The  seriousness  of  the  disaster  is  greatly  augmented  by  the 
fact  that  the  consequences  of  neglect  are  usually  not  apparent  until 
after  the  goods  have  reached  the  market.  The  pollution  of  con- 
densed milk  with  impurities  and  filth  in  the  factory,  shortens  the 
life  of  the  product.  Such  condensed  milk  is  of  very  poor  keeping 
quality.  It  may  reach  the  market  and  the  consumer  in  condition 
that  causes  it  to  be  rejected,  resulting  in  a  complete  loss  to  the  man- 
ufacturer. The  manufacturer  allowing  such  conditions  to  exist, 
is  usually  the  last  man  to  realize  and  admit  that  he  is  at  fault,  which 
renders  attempts  to  locate  and  stop  such  defects  exceedingly  difficult. 
Furthermore,  instead  of  helping  to  build  up  the  trade  and  to  adver- 
tise the  brand,  he  demoralizes  it. 

How  to  Keep  Factory  in  Sanitary  Condition. —  Cleanliness  in 
•the  factory  is  absolutely  essential.  The  milk  vats  should  be  rinsed 
with  plenty  of  water  and  scrubbed  and  steamed  thoroughly,  as  soon 


FACTORY  SANITATION  51 

as  possible  after  use.  The  copper  kettles  and  vacuum  pans  should 
be  rinsed,  then  scoured  with  sandpaper  or  emery  cloth,  then  rinsed 
and  steamed  thoroughly.  The  milk  pipes  should  be  scoured  by  run- 
ning flue  brushes  through,  flushing  them  with  clean  water  and 
steaming  them  until  they  are  scalding  hot.  In  the  case  of  milk 
pipes  of  excessive  length,  they  should  be  well  flushed  with  hot  alka- 
line water.  Milk  pumps  should  be  taken  apart  every  day  and  freed 
thoroughly  from  all  remnants  of  milk.  The  water  in  the  cooling 
tanks  should  be  changed  as  often  as  is  necessary  to  insure  clean 
water  in  them  at  all  times.  The  homogenizer  should  receive  special 
attention,  all  its  valves  should  be  thoroughly  cleaned  and  steamed 
daily.  The  cooling  coils  should  be  scalded  before  use.  The  filling 
machines  for  evaporated  milk  should  be  freed  from  all  milk,  rinsed 
and  steamed  thoroughly  and  no  remnants  of  milk  should  be  allowed 
to  stick  to  the  valves.  The  filling  machines  for  sweetened  con- 
densed milk  should  be  emptied  and  completely  washed,  at  least  once 
per  week,  and  protected  from  dust  and  filth  by  covering  them  when 
not  in  use.  The  tin  cans  should  be  stored  in  a  clean  room  and  every 
precaution  should  be  taken  to  guard  against  their  defilement  from 
dirt,  dust,  insects  and  mice.  Where  possible  they  should  be  steril- 
ized before  use. 

All  vats,  kettles,  milk  conveyors,  vacuum  pans  J  milk  pumps,  and 
all  machinery  coming  in  contact  with  milk,  should  be  flushed  and 
steamed  again  in  the  morning,  as  soon  as  the  condensery  opens. 
The  sugar  chute  should  be  kept  clean,  care  beitig  taken  that  no 
damp  or  wet  sugar  remains  in  it.  Special  attention,  should  be  given 
to  the  washing  of  the  farmers'  cans.  After  washing  with  brush  and 
hot  water  containing  some  good  washing  powder,  they  should  be 
thoroughly  rinsed,  then  steamed  until  they  are  hot.  If  possible 
they  should  be  dried  by  an  air  blast. 

The  floors  and  walls  of  the  factory  should  be  kept  in  sanitary 
condition.  Accumulated  rubbish  should  be  removed  and  sewers 
and  drains  should  be  disinfected  at  regular  intervals. 

Care  of  Milk  in  the  Factory  Prior  to  Manufacture. — The 
problem  of  so  handling  the  milk  in  the  factory,  from  the  time  it 
arrives  until  it  is  heated  preparatory  to  evaporation,  is  an  important 
one,  that  has  received  much  careful  consideration  by  the  foremost 
condensed  milk  men.  Since  bacteriological  analyses  have  shown 
that,  under  favorable  temperature  conditions,  the  micro-organisms 


52 


FACTORY  SANITATION 


present  in  milk  are  capable  of  doubling  in  number  once  every  twenty 
minutes,  it  is  essential  that  the  milk  either  be  heated  to  high  enough 
temperatures  to  destroy  germ  life,  or  be  cooled  to  a  temperature  low 
enough  to  stop  growth  and  multiplication,  as  soon  as  possible. 

Both  practices  are  feasible,  but  to  heat  the  large  volumes  of 
milk  that  arrive  at  the  factory,  all  within  a  few  hours,  would  tax 
the  equipment  of  the  factory  under  average  conditions  very  heavily. 
And  unless  the  condensery  were  equipped  with  very  large  vacuum 
pan  capacity,  much  of  this  heated  milk  would  have  to  lie  idle  in  the 


Fig.   10.     Glass-lined   tank  for  cooling   and   holding   milk  before   manufacture 
Courtesy  of  The  Pfaudler  Company 

forewarmers  for  hours,  awaiting  its  turn  for  condensation.  This 
would  be  undesirable  and  might  prove  harmful  to  the  quality  of  the 
finished  product. 

Efforts  have,  therefore,  been  made,  especially  within  recent, 
years,  to  provide  a  practical  and  economical  method  of  cooling  the 
milk  as  soon  as  it  arrives  and  of  holding  it  at  a  low  temperature 
until  ready  for  heating  and  condensing.  This  has  led  to  diverse 
practices,  such  as  running  the  milk  over  a  surface  coil  cooler  into 


FACTORY  SANITATION  53 

a  jacketed  tank,  or  cooling  it  by  running  it  into  a  large  tank  equipped 
with  cold  air  blowers,  etc. 

The  latest  improved  method  for  refrigerating  the  milk  consists 
of  the  use  of  large,  usually  circular,  glass  enameled  steel  tanks. 
These  tanks  are  completely  surrounded  on  their  sides  and  bottom 
by  a  cold  water  or  brine  jacket  and  are  equipped  with  a  milk  dis- 
tributing device  that  causes  the  inflowing  milk  to  be  sprayed  by 
gravity  against  the  top  of  the  sides  of  the  tank  and  to  percolate  in 
a  thin  layer  down  the  sides.  In  this  manner  the  cooling  is  in- 
stantaneous, the  entire  sides  of  the  tank  being  surrounded  by  the 
cooling  medium.  It  is  aimed  to  cool  the  milk  to  about  40  to  45 
degrees  F.  and  to  hold  it  at  this  temperature  until  ready  for  manu- 
facture. 

These  glass  enameled  tanks  have  many  advantages ;  they 
minimize  the  initial  cost  of  the  necessary  equipment,  reducing  the 
number  of  costly  vacuum  pans,  and  f  orewarmers,  required ;  they 
cut  down  labor  cost,  because  they  reduce  the  equipment  to  fewer 
pieces  to  operate  and  to  clean ;  they  are  of  such  construction  that 
they  are  easily  and  quickly  cleaned  and  readily  kept  in  proper 
sanitary  condition,  the  smooth  and  pore-free  enamel  yields  more 
readily  to  the  brush  than  copper  surfaces ;  they  avoid  all  possibility 
of  chemical  action  of  the  milk  on  metal  and,  therefore,  are  a 
reliable  safeguard  against  the  development  of  metallic  flavor  in 
the  milk. 

The  use  of  these  large  holding  tanks  also  facilitates  the  stand- 
ardization of  the  milk  for  fat  and  solids  not  fat.  For  detailed  direc- 
tions on  standardizing  see  Chapter  XXIX,  page  253. 


PART  II. 

MANUFACTURE  OF  SWEETENED 
CONDENSED  MILK 

CHAPTER  IV. 
DEFINITION 

Sweetened  condensed  milk  is  cow's  milk,  condensed  at  the  ratio 
of  2Y-2  to  2^4  parts  of  fresh  milk  to  1  part  condensed  milk.  It  con- 
tains considerable  quantities  of  sucrose,  usually  about  40  per  cent, 
to  preserve  it.  It  is  of  semi-fluid  consistency  and  reaches  the  market 
in  hermetically  sealed  tin  cans,  varying  in  size  from  eight  ounces  to 
one  gallon,  and  in  barrels  similar  to  glucose  barrels,  holding  from 
three  hundred  to  seven  hundred  pounds  of  condensed  milk.  When 
made  properly,  sweetened  condensed  milk  will  keep  for  many 
months,  but  is  best  when  fresh. 

HEATING 

Purpose. — The  first  step  in  the  process  is  to  heat  the  milk  to 
near  the  boiling  point.  There  are  three  chief  reasons  for  which  the 
milk  is  heated,  namely,  to  destroy  most  of  the  bacteria,  yeast,  molds 
and  other  organized  and  unorganized  ferments,  to  facilitate  the 
solution  of  the  sucrose,  and  to  prevent  the  milk  from  burning  on  to 
the  heating  surface  in  the  vacuum  pan. 

DESTRUCTION  OF  FERMENTS. — When  the  fresh  milk  arrives  at 
the  factory  it  contains  micro-organisms  in  varying  numbers  and  of 
different  species.  In  some  cases  disease-producing  bacteria  may  be 
present,  rendering  the  milk  dangerous  to  the  health  and  life  of  the 
consumer,  were  it  not  heated  to  temperatures  high  enough  to  destroy 
these  germs.  Again,  milk  may  contain  bacteria,  yeast,  molds  and 
enzymes  that  cause  it  to  undergo  undesirable  fermentations  which, 
if  allowed  to  pass  into  the  condensed  milk,  may  tend  to  shorten  the 
life  and  impair  the  wholesomeness  and  marketable  properties  of 
the  latter. 

SOLUTION  OF  SUCROSE. — It  is  very  essential  that  all  the  cane 
sugar  which  is  added  to  the  milk  be  completely  dissolved,  in  order 


CONDENSED  MILK — HEATING  55 

to  lessen  the  tendency  of  the  sugar  to  crystallize  in  the  finished 
product.  Undissolved  sugar  crystals  in  condensed  milk  act  in  a 
physical  way  much  as  bacteria  in  fluid  milk  do  in  a  bacteriological 
way.  They  multiply  rapidly,  and  such  condensed  milk  usually 
precipitates  its  sugar  before  the  product  reaches  the  market.  The 
presence  of  excessive  sugar  crystals  makes  the  product  gritty  and 
causes  the  formation  of  a  sediment  in  the  bottom  of  the  cans ;  this 
is  objectionable  to  the  consumer.  When  the  milk  is  heated  to  the 
proper  temperature  before  condensing,  the  solution  of  the  cane 
sugar  is  facilitated  and  the  tendency  toward  grittiness  is  minimized. 

PREVENTION  OF  BURNING  MILK  ON  HEATING  SURFACE.— If  cold 
milk  comes  in  contact  with  a  steam-heated  surface  and  is  not  agi- 
tated vigorously,  it  bakes  or  burns  onto  this  heating  surface.  The 
milk  in  the  vacuum  pan  is  heated  or  kept  hot  by  means  of  the  steam 
jacket  and  coils.  These  radiators  are  charged  with  steam  under 
pressure  and  consequently  give  off  a  high  degree  of  heat.  If  cold 
milk  is  drawn  into  the  vacuum  pan,  the  milk  remains  calm  for  a 
considerable  length  of  time.  During  this  time  it  is  bound  to  bake 
or  burn  on  the  heating  surface,  giving  the  product  a  burnt  flavor, 
causing  it  to  contain  brown  specks  and  retarding  the  process  of 
evaporation.  If  the  milk  is  hot  when  it  enters  the  pan,  the  reduced 
pressure  in  the  pan  causes  it  to  boil  violently  at  once,  avoiding  all 
danger  of  sticking  to  and  burning  on  the  heating  surface  and  making 
possible  maximum  rapidity  of  evaporation. 

Temperature. — In  most  factories  the  milk  is  heated  to  from 
180  degrees  F.  to  200  degrees  F.  This  temperature  is  sufficient  to 
accomplish  the  three  purposes.  Heating  the.  milk  to  the  boiling  point 
tends  to  give  it  a  rather  pronounced  cooked  flavor,  which  is  objec- 
tionable. However,  in  the  case  of  danger  of  contamination  of  the 
milk  with  resistant  types  of  undesirable  bacteria,  it  may  become 
necessary  to  practice  boiling  the  milk. 

Manner  of  Heating. — Thorough,  efficient  and  rapid  heating  of 
large  volumes  of  milk  to  temperatures  near  the  boiling  point  is  a 
problem  that  requires  careful  consideration.  The  tendency  of  the 
milk  to  stick  to  the  heating  surface  is  a  permanent  obstacle  and 
efforts  to  overcome  this  frequently  result  in  sacrificing  thoroughness 
of  heating. 


56 


SWEETENED  CONDENSED  MILK — HEATING 


A  variety  of  methods  and  numerous  different  types  of  machines 
are  used  for  this  purpose  in  the  different  milk  condensing  factories. 
Some  use  large  copper  kettles  in  which  the  milk  is  heated  by  turning 
steam  direct  into  the  milk.  Others  use  jacketed  copper  kettles 
equipped  with  a  revolving  agitator.  The  milk  is  heated  by  turning 

steam  under  pressure  into  the  jacket 
and  the  burning  of  the  milk  is  pre- 
vented by  keeping  the  milk  in  constant 
motion.  Still  others  are  heating  the 
milk  by  means  of  large  continuous 
pasteurizers  in  which  case  hot  water 
or  steam  serves  as  the  heating  medium. 
The  milk  passes  in  a  thin  layer  be- 
tween two  water-heated  surfaces,  one 
of  which  is  revolving.  In  some  fac- 
tories the  milk  is  forced  through  a 
series  of  pipes  inclosed  in  a  hot  water 
or  steam  jacket. 

Finally,  in  some  condenseries  a 
combination  of  the  continuous  pas- 
teurizer and  the  jacketed  kettle  is 
used.  The  milk  is  heated  to  nearly  the  desired  temperature  in  the 
pasteurizer.  From  there  it  flows  into  the  jacketed  kettle.  This 
kettle  is  so  constructed  that  when  steam  is  turned  into  the  jacket, 
the  milk  rises  and  it  flows  over  and  off  into  the  sugar  well.  This 
insures  efficient  heating  and,  at  the  same  time,  if  operated  properly, 
it  prevents  the  baking  of  the  milk  on  the  heating  surface.  The 
disadvantage  of  this  double  system  of  heating  is  that  the  overflow- 
ing kettle  has  to  be  watched  very  closely. 

Advantages  and  Disadvantages  of  Different  Methods  of 
Heating. — In  most  factories  in  this  country  the  first  named  method 
is  used.  Steam  is  turned  direct  into  the  milk  until  it  boils  up.  This 
is  the  oldest  and  most  primitive  method.  While  very  simple  in 
operation,  this  method  has  serious  objections.  At  best,  much  of  the 
steam  used  condenses  in  the  milk,  increasing  the  amount  of  water 
that  has  to  be  evaporated.  It,  therefore,  prolongs  the  process  of 
condensing  and  increases  the  cost  of  manufacture.  This  is  espe- 
cially true  where  the  boilers  are  located  at  some  distance  from  the 
hot  wells  and  the  steam  pipes  are  not  well  insulated,  causing  the 


Fig.    11. 

The    hot   well    OP   forewarmer 
Courtesy  of  Arthur  Harris  &  Co. 


SWEETENED  CONDENSED  MILK — ADDITION  OF  SUGAR         57 

steam  to  be  "wet."  It  is  estimated  that  the  amount  of  extraneous 
water  thus  added  to  the  milk  increases  the  bulk  of  the  milk  by  about 
one-sixth  of  its  original  volume.  The  steam  is  often  associated 
with  impurities,  such  as  cylinder  oil  from  the  engine,  boiler  com- 
pounds used  in  the  boilers,  scales  from  the  inside  of  the  pipes,  etc. 
These  various  impurities  cannot  possibly  improve,  but  may  seriously 
injure  the  quality  of  the  milk.  It  is  quite  probable,  also,  that  the 
direct  contact  of  live  steam  with  milk  has  no  beneficial  effect  on  its 
ingredients.  It  is  generally  conceded  by  those  who  have  given  this 
matter  careful  thought,  that  the  turning  of  steam  direct  into  the 


Fig.   12.     Steam   rosette  for   heating    milk 
Courtesy   of   Arthur  Harris   &   Co. 

milk  shortens  the  life  of  the  product  and  causes  it  to  develop  a  stale 
flavor,  which  may  degenerate  into  an  oily  flavor.  The  same  defect 
is  noted  also  when  cream  is  heated  by  turning  steam  into  it.  The 
prolonged  exposure  of  the  milk  to  the  condensing  process,  as  the 
result  of  the  addition  to  the  milk  of  considerable  quantities  of  con- 
densed steam,  further  may  be  injurious  to  the  milk. 

Any  method  of  heating  that  does  not  require  direct  contact  of 
the  steam  with  the  milk  is  preferable,  provided  that  it  makes  possible 
thorough  heating  to  the  required  temperature  without  burning  the 
milk.  Practically  all  of  the  other  methods  above  referred  to  accom- 
plish this  when  properly  applied. 

ADDITION  OF  SUGAR 

Considerable  quantities  of  sucrose  are  added  to  the  condensed 
milk  for  the  purpose  of  preserving  it. 

Kinds  of  Sugar. —  In  order  to  convey  to  the  milk  preservative 
properties,  that  kind  of  sugar  must  be  used  which  does  not  readily 


58  SWEETENED   CONDENSED  MlI,K — ADDITION   OF   SUGAR 

undergo  fermentation  and  which  has  the  power  of  inhibiting  bac- 
terial activity  when  dissolved  in  a  concentrated  solution.  Glucose 
could  be  purchased  at  a  very  low  cost,  but  it  is  not  suitable  for  this 
purpose,  since  it  is,  in  itself,  very  unstable  and  fermentable.  It  has 
no  preservative  qualities,  even  in  concentrated  solutions.  Sucrose, 
saccharose,  or  cane  sugar,  C^H^O^,  properly  refined,  ferments 
with  difficulty  in  concentrated  solutions,  and  has  the  power  of  re- 
tarding the  growth  of  bacteria  and  other  ferments  ordinarily  present 
in  sweetened  condensed  milk.  It  is,  therefore,  very  satisfactory  and 
useful  in  this  connection. 

Beet  sugar,  which  is  chemically  identical  with  cane  sugar,  is 
used  in  European  countries  very  largely  in  the  place  of  cane  sugar. 
On  the  continent  the  beet  sugar  industry  is  an  important  factor. 
With  the  climate  adapted  to  the  growing  of  sugar  beets  and  the 
labor  relatively  cheap,  beet  sugar  can  be  secured  by  the  European 
condenseries  at  lower  cost  than  cane  sugar.  In  America,  where  the 
annual  sugar  cane  crop  is  large  and  where  the  high  cost  of  labor 
renders  the  expense  of  growing  sugar  beets  relatively  high,  there 
is  practically  no  difference  between  the  price  of  cane  sugar  and  beet 
sugar.  When  American  beet  sugar  was  used  in  the  condenseries 
during  the  infancy  of  the  beet  sugar  industry,  this  sugar  was  found 
undesirable,  often  giving  rise  to  fermented  condensed  milk.  It  was 
then  supposed  by  the  condensed  milk  men  that  beet  sugar  contained 
very  resistant  spore-bearing  bacteria,  which  followed  the  beets  from 
the  soil  into  the  refined  sugar.  This  conclusion  is  highly  improbable, 
as  the  temperatures  and  chemicals  employed  in  the  process  of  beet 
sugar  making  are  prohibitive  of  the  passage  of  living  bacteria  from 
the  soil  to  the  finished  sugar.  It  is  possible,  however,  that  the 
standard  of  refinement  of  American  beet  sugar,  during  the  earlier 
days  of  its  manufacture,  was  low  and  that  some  of  the  beet  sugar 
on  the  market  may  have  contained  small  amounts  of  acid,  invert 
sugar  and  other  impurities,  ingredients  of  such  a  nature  as  to  render 
the  sugar  prone  to  give  rise  to  fermentation  and,  therefore,  condemn 
its  use  in  the  milk  condensery. 

While  the  beet  sugar  on  the  market  today  appears  to  have 
reached  a  very  high  state  of  refinement  and  is,  according  to  the  best 
authorities,  equal  in  purity  to  cane  sugar,  it  is  still  shunned  by  the 
American  condenseries,  which  insist  that  nothing  but  cane  sugar  will 
do.  However,  the  total  beet  sugar  production  in  the  United  States 


CONDENSED  MILK — ADDITION  OF  SUGAR         59 

has  more  than  trebled  within  the  last  ten  years.  In  1901  it  amounted 
to  one  hundred  eighty-four  thousand  tons  and  in  1911  it  was  six 
hundred  six  thousand  and  thirty-three  tons.  Again,  whenever  a 
shortage  occurs  of  the  sugar  cane  crop  in  the  West  Indies,  raw 
European  beet  sugar  is  imported  into  the  United  States  and  it  all 
emerges  from  our  seaboard  refineries  as  "pure  cane  sugar."  It  is 
not  improbable,  therefore,  that  the  sugar  supply  of  many  American 
condenseries  today  consists  at  times  largely  of  beet  sugar,  though  it 
is  purchased  under  the  name  of  cane  sugar. 

There  is  no  good  reason  why  the  best  refined  beet  sugar,  manu- 
factured today  in  this  country  and  elsewhere,  should  not  give  fully 
as  good  results  for  condensing  purposes  as  the  same  quality  of  cane 
sugar.  Tests  made  at  the  California  Agricultural  Experiment  Sta- 
tion1 led  to  the  conclusion  that  the  two  kinds  of  sugar,  cane  sugar 
and  beet  sugar,  were  equally  valuable  for  canning  and  identical  in 
their  behavior  when  of  the  same  fineness  of  crystallization. 

BEET  SUGAR  CANNOT  BE  DETECTED  FROM  CANE  SUGAR. — While 
the  raw  sugar  from  the  two  different  sources,  the  sugar  cane  and 
the  sugar  beet,  takes  on  the  character  of  the  impurities  from  which 
it  has  not  yet  been  freed  (the  raw  product  of  the  sugar  cane  is 
pleasant  in  flavor,  the  raw  product  from  the  sugar  beet  is  acrid  and 
disagreeable  in  flavor),  the  sucrose  or  so-called  pure  cane  sugar, 
can  be  and  is  crystallized  out,  and  in  every  case  the  sugar  is  identical 
in  chemical  composition,  appearance  and  properties.  "By  no  chem- 
ical test  can  the  pure  crystallized  sugar  from  these  two  different 
sources  be  distinguished."2 

Quality  of  the  Sugar. —  Since  the  sugar,  sucrose,  is  added  for 
the  purpose  of  preserving  the  condensed  milk,  it  is  obvious  that  none 
but  the  best  quality  of  refined  sucrose  is  admissible.  Low  grade 
sucrose  is  a  product  dangerous  to  the  condensed  milk  business.  It 
is  apt  to  contain  sufficient  quantities  of  acid  and  invert  sugar,  to  give 
bacteria  and  yeast  an  opportunity  to  start  fermentation.  When 
once  started,  the  destruction  of  the  product  is  almost  inevitable.  In 
years  of  failure  of  the  cane  sugar  crop,  when  the  prices  of  sucrose 
soar  high,  condenseries  yield  frequently  to  the  temptation  of  buying 
lower  grades  of  sugar.  The  result  invariably  is  an  abnormally  large 
output  of  condensed  milk  that  "goes  wrong." 

1  California  Agricultural  Experiment  Station,   Circular  No.  33. 

2  United  States  Department  of  Agriculture,  Farmers'  Bulletin  No.  535,  1913. 


60         SWEETENED  CONDENSED  MILK — ADDITION  OF  SUGAR 

It  is  very  important  that  the  sugar  in  the  factory  be  stored 
where  it  will  keep  dry.  Sucrose  has  hygroscopic  properties.  When 
exposed  to  an  atmosphere  saturated  with  moisture  it  absorbs  water. 
In  damp  storage  it  is  prone  to  become  lumpy,  moldy  and  frequently 
sour.  When  these  precautions  are  neglected  there  is  danger  of  de- 
fective condensed  milk,  causing  the  cans  on  the  market  to  swell,  due 
to  gaseous  fermentation. 

When  the  sugar  reaches  the  milk  through  a  chute  from  the 
floor  above,  the  sugar  chute  and  similar  conveyors  must  be  kept 
clean  and  dry.  The  lower  end  of  the  sugar  chute  is  usually  located 
directly  over  the  steaming  milk  in  the  well  room.  In  such  cases 
there  is  always  more  or  less  danger  of  condensation  in  the  chute  of 
the  vapors  from  the  milk  below.  This  causes  the  sugar  to  stick  to 
and  form  a  crust  on  the  inside  of  the  chute.  This  moist  crust  of 
sugar,  when  contaminated  with  bacteria,  yeast  or  molds,  is  prone  to 
start  fermenting.  When  portions  of  this  sour  crust  peel  off  and  are 
carried  into  the  milk  below,  they  may  cause  entire  batches  of  con- 
densed milk  to  spoil,  as  the  result  of  gaseous  fermentation. 

Adulteration  of  sugar  with  foreign  admixtures,  such  as  white 
sand,  white  clay,  starch,  or  lime  dust  is  rare,  and  occurs  usually  only 
in  pulverized  sugar.  For  the  detection  of  these  adulterants,  add  a 
spoonful  of  the  suspicious  sugar  to  a  glass  of  hot  water  and  stir. 
Pure  sugar  will  dissolve  completely,  while  most  of  the  common  im- 
purities are  insoluble  and  will  settle  to  the  bottom. 

The  purchase  of  coarsely  granulated  sugar  is  an  effective  safe- 
guard, insuring  freedom  from  these  adulterants.  Powdered  sugar 
should  not  be  used  in  the  condensery. 

Amount  of  Sugar. — The  amount  of  sucrose  used  varies  in  dif- 
ferent countries,  with  different  manufacturing  concerns,  in  different 
factories  of  the  same  company  and  at  different  seasons  of  the  year. 
The  normal  variations  range  between  twelve  and  eighteen  pounds 
of  sucrose  per  one  hundred  pounds  of  fresh  milk.  Most  factories 
use  about  16  per  cent. 

It  is  not  advisable  to  overstep  the  limits  above  indicated.  Con- 
densed milk  serves  as  a  substitute  for  fresh  milk.  The  more  sucrose 
it  contains,  the  greater  is  the  difference  in  composition  and  prop- 
erties between  the  condensed  milk  and  the  fresh  milk.  Sucrose  is 
not  as  readily  digested  as  the  other  ingredients  of  milk;  therefore, 


SWEETENED  CONDENSED  MILK — ADDITION  OF  SUGAR        61 

the  presence  of  excessive  amounts  of  cane  sugar  in  condensed  milk 
tends  to  reduce  its  digestibility  and  its  wholesomeness  as  a  food. 
Again,  while  normal  milk  is  a  well-balanced  food  in  itself,  the  pres- 
ence of  large  amounts  of  cane  sugar  in  it  causes  this  equilibrium  to 
be  disturbed,  the  condensed  milk  being  excessively  rich  in  carbo- 
hydrates and  relatively  poor  in  proteids.  These  facts  are  specially 
significant  where  condensed  milk  is  used  for  infant  feeding  and  by 
persons  with  weak  digestion. 

On  the  other  hand,  sweetened  condensed  milk  depends  for  its 
preservation  on  the  sucrose.  This  class  of  condensed  milk  is  not 
sterile  and  is  prevented  from  rapid  deterioration  by  the  preservative 
action  of  the  sucrose  only.  Therefore,  the  smaller  the  amount  of 
sucrose  it  contains,  the  greater  the  danger  from  the  activity  of  fer- 
ments and  the  less  its  keeping  quality. 

The  relative  prices  of  cane  sugar  and  of  fresh  milk  also  govern 
the  amount  of  cane  sugar  used  in  many  factories.  In  summer,  milk 
prices  are  low  and  sugar  prices  are  high,  while  in  winter  the  rela- 
tive prices  are  reversed.  Hence  there  is  a  tendency  on  the  part  of 
the  manufacturer  to  use  less  sugar  in  summer  than  in  winter. 

Again,  the  amount  of  cane  sugar  used  varies  according  to  the 
kind  of  market  for  which  the  condensed  milk  is  intended.  Milk  put 
on  the  market  in  hermetically  sealed  cans  is  generally  exposed  to 
more  unfavorable  conditions  and  is  older  by  the  time  it  reaches  the 
consumer  than  milk  sold  in  barrels.  It  is  customary  to  use  about 
sixteen  pounds  of  cane  sugar  for  every  one  hundred  pounds  of  fresh 
milk  for  canned  goods,  and  about  twelve  to  fourteen  pounds  of  cane 
sugar  for  barrel  goods. 

Finally,  there  is  a  strong  tendency  in  some  localities  for  sweet- 
ened condensed  milk  made  in  May  and  June,  to  thicken  rapidly 
and  become  cheesy  with  age.  This  can  easily  be  prevented  by  the 
use  of  more  cane  sugar  in  the  milk  manufactured  during  these 
months.  (See  Chapter  XXIII  on  "Condensed  Milk  Defects.") 

Mixing  the  Sugar. — The  sugar  is  added  to  the  hot  milk  before 
the  latter  enters  the  vacuum  pan.  In  some  factories  a  separate  tank 
is  provided  for  this  purpose.  Small  portions  of  the  hot  milk  are 
allowed  to  flow  into  this  tank.  To  these  the  sugar  is  added.  This 
tank  is  called  the  sugar  well.  It  is  usually  equipped  with  a  mechan- 


62  Sw££¥ENBD  CONDENSED  MILK — CONDENSING 

ical  reversible  stirrer,  moving  to  and  fro  on  an  eccentric,  to  facilitate 
the  solution  of  the  sugar.  The  milk  from  the  heater  and  from  the 
sugar  well  runs  into  a  tank  sunk  into  the  floor  of  the  well  room,  the 
ground  well,  from  which  the  mixed  sweetened  milk  is  drawn  into 
the  vacuum  pan.  In  other  factories  the  sugar  well  and  ground  well 
are  one  and  the  same  tank,  into  which  the  milk  runs  direct  from  the 
heater.  In  this  case  it  is  advisable  to  set  a  wire  mesh  strainer  (sixty 
to  eighty  meshes  to  the  inch)  over  the  sugar  well.  The  sugar  is 
placed  into  this  strainer,  a  little  at  a  time ;  the  hot  milk  from  the 
heater  passing  into  and  through  the  strainer  dissolves  the  sugar. 
A  paddle  or  stick  should  be  used  to  stir  the  sugar  in  the  strainer. 
For  greater  convenience  and  economy  of  labor,  the  sugar  barrels 
and  scales  are  placed  on  the  floor  over  the  well  room.  The  sugar 
is  transferred  to  the  strainer  below  through  a  sugar  chute  which 
may  be  equipped  at  the  lower  end  with  an  adjustable  cut-off  to  reg- 
ulate the  sugar  coming  down.  Other  factories  dissolve  their  sugar 
in  boiling  water  in  a  separate  tank,  and  draw  this  syrup  into  the 
vacuum  pan  together  with  the  hot  milk.  This  is  a  very  commend- 
able practice,  as  it  minimizes  the  danger  of  undissolved  sugar  crys- 
tals to  escape  into  the  pan.  Moreover,  this  watery  syrup  can  be 
boiled  without  danger  of  giving  the  milk  a  cooked  flavor. 

CHAPTER  V 
CONDENSING 

From  the  ground  well  in  the  well  room  the  sweetened  milk  is 
drawn  into  the  vacuum  pan,  where  it  is  condensed  under  reduced 
pressure.  The  vacuum  pan  is  usually  located  on  the  second  floor 
over  the  well  room,  or  in  the  well  room  itself,  in  which  case  it  is 
elevated  above  the  floor  six  to  eight  feet.  The  vacuum  pan  is  con- 
nected with  the  vacuum  pump,  which  should  be  installed  near 
the  pan. 

Description  of  the  Vacuum  Pan. — The  vacuum  pan  is  a  re- 
tort in  which  the  milk  is  heated  and  evaporated  in  partial  vacuum. 
The  origin  of  the  term  "pan"  has  not  been  satisfactorily  explained. 
In  the  early  and  experimental  days  of  the  manufacture  of  con- 
densed milk,  the  milk  was  evaporated  in  open  kettles,  called  pans. 


SWEETENED  CONDENSED  MILK — CONDENSING  63 

It  is  probable  that  the  name  of  this  primitive  apparatus  was  passed 
on  to  the  more  perfected  machinery  now  in  use. 

The  vacuum  pans  are  constructed  of  copper,  iron,  steel  or 
bronze.  Practically  all  of  the  vacuum  pans  used  for  condensing 
milk  are  made  of  copper  throughout ;  they  are  of  various  styles 
and  sizes.  The  predominating  size  used  in  milk  condenseries  is 
the  "six-foot  pan."  By  the  term  six-foot  is  meant  a  retort  meas- 
uring six  feet  in  diameter. 

There  are  two  general  types  of  vacuum  pans  on  the  market ; 
pans  that  are  relatively  wide  in  diameter  and  shallow  in  depth,  and 
pans  of  relatively  narrow  diameter  and  which  have  a  deep  body. 
Both  types  are  claimed,  by  their  respective  manufacturers,  to  have 
special  advantages,  such  as  ease  of  operation,  uniformity  of  action, 
economy  of  fuel  and  of  water,  and  rapidity  of  evaporation ;  the 
opinions  of  the  users  of  these  pans  are  also  at  variance  concerning 
their  relative  merits. 

The  advocates  of  the  wide,  shallow  pan  claim  that  this  type 
of  pan  makes  possible  such  an  arrangement  of  the  heating  surface 
as  to  take  care  of  the  maximum  amount  of  milk  with  the  minimum 
depth  of  milk  over  the  heating  surface  and  that  this  arrangement 
is  most  desirable.  They  hold  that  because  the  wide  and  shallow 
pan  offers  a  larger  area  of  evaporating  surface,  it  therefore  makes 
possible  more  rapid  evaporation  than  the  narrow,  deep  pan.  They 
further  emphasize  that  in  the  wide,  shallow  pan,  the  milk  boils 
more  quietly,  is  under  better  control  and  is  less  apt  to  be  carried 
over  into  the  condenser  and  lost,  than  in  the  narrow,  deep  pan. 

The  advocates  of  the  narrow,  deep  pan  claim  that  their  type 
of  pan  increases  the  rapidity  of  evaporation  because  it  causes  the 
milk  to  pass  over  the  heating  surface  more  rapidly.  When  the 
pan  is  in  operation,  the  boiling  milk  travels  from  the  center  of  the 
bottom  toward  the  periphery  where  it  rises,  rolls  over  the  coils, 
and  returns  to  the  center.  It  is  claimed  that  a  pan  with  a  shallow 
jacket,  such  as  the  narrow,  deep  pans  have,  causes  the  milk  to  roll 
over  higher,  especially  if  the  coils  are  close  to  the  periphery  and 
leave  plenty  of  vacant  space  in  the  center  of  the  pan.  This,  in  turn, 
means  more  rapid  circulation  of  the  milk,  causing  it  to  pass  over 
the  heating  surface  at  greater  speed,  and  oftener,  which  naturally 
enables  the  milk  to  utilize  more  heat  and,  therefore,  to  evaporate 


64  SWEETENED  CONDENSED  MILK — CONDENSING 

more  quickly.     Because  in  such  pans  the  milk  rolls  over  higher, 
they  require  a  deeper  body. 


Fig.   13. 
Vacuum    pan    and    condenser 

Courtesy   of 
Arthur  Harris  &  Co. 


The  vacuum  pan  consists  of  four  main  parts,  namely,  the  jacket, 
the  body,  the  dome,  and  the  condenser. 

The  jacket  forms  the  bottom  of  the  pan.  The  inside  wall  is 
copper,  the  outside  cast  iron.  It  is  concave  and  in  the  case  of  a 
six-foot  pan  about  two  and  one-half  feet  deep.  It  is  equipped  with 
two  steam  inlets  and  one  outlet.  The  outlets  for  the  coils  are  usually 
also  brought  through  the  jacket.  In  the  center  of  the  bottom  there 
is  an  opening,  two  to  three  inches  in  diameter,  for  the  discharge 
of  the  condensed  milk  and  fitted  with  two  valves  and  a  nipple 
between,  to  facilitate  the  sampling  of  the  condensed  milk. 


SWEETENED  CONDENSED  MILK — CONDENSING  65 

The  body  or  vapor  belt 
represents  the  main  part  of  the 
pan.  It  is  cylindrical,  of  vary- 
ing height  and  is  equipped  with 
copper  coils  which  have  their 
outlets  through  the  jacket.  Their 
upper  ends  connect,  through  the 
body  of  the  pan,  with  the  main 
steam  line.  Most  pans  are 
equipped  with  two  to  three  coils 
located  at  different  elevations. 
Since  steam  should  be  turned 
into  the  coils  only  when  they 
are  covered  with  the  milk,  it  is 
desirable  to  have  several  short 
independent  coils  rather  than  but 
one  large  one.  This  will  give  a 
larger  range  of  the  quantity  of 
milk  that  can  be  condensed  and  Fig>  14'  Vacuum  pan  and  condenser 

Courtesy  of   C.   E.   Rogers 

increases  the  speed  of  evapora- 
tion. The  t  coils  -vary  in  diameter  from  about  three  to  five  inches. 
The  upper  and  outer  coils  are  the  larger  ones.  The  diameter  and 
length  of  the  coils  necessarily  vary  with  and  are  limited  by  the 
capacity  of  the  pan.  The  greater  the  total  heating  surface,  consistent 
with  easy  access  to  all  parts  of  the  jacket  and  coils,  the  better. 
Other  things  being  equal,  the  more  square  feet  of  heating  surface, 
the  less  steam  pressure,  by  the  gauge,  is  required  to  furnish  the 
necessary  heat  for  maximum  evaporation.  This  is  important 
because  high  steam  pressure  in  the  jacket  and  coils  means  exposure 
of  the  milk  to  high  temperature,  which  is  undesirable.  The  heating 
surface  should  be  sufficient  to  make  possible  the  complete  con- 
densation of  the  steam  in  the  jacket  and  coils.  If  the  heating 
surface  is  inadequate,  more  steam  has  to  be  turned  into  the  jacket 
and  coils,  in  order  to  secure  the  necessary  heat  for  rapid  evapora- 


66 


D  CONDENSED  MILK  —  CONDENSING 


r 


Fig.  15.     Covering  and   insulation  for  vacuum   pans 
Courtesy   of  Arthur   Harris   &   Co. 

tion,  than  will  condense;  free  steam  will  blow  through  and  out  of 

the  coils,  resulting  in  uneconomic 
and  wasteful  use  of  fuel,  and 
jeopardizing  the  quality  of  the 
product.  A  properly  constructed 
six-foot  pan  usually  has  not  less 
than  one  hundred  twenty  to  one 
hundred  thirty  square  feet  of 
heating  surface. 

In  the  latest  improvement 
in  coils  each  independent  coil 
makes  only  one  turn  in  the  pan 
and  the  inner  and  outer  coils 
have  the  same  inlet  and  dis- 
charge and  are  placed  on  the 
same  level.  This  permits  of  the 
installation  of  a  larger  number  of  independent  coils,  each  placed  at  a 
different  level.  In  this  manner  the  coils  can  be  utilized  to  better 
advantage.  This  is  especially  significant  when  the  volume  of  milk 


Fig.    16.     Steam   coils 
Courtesy  of  Arthur  Harris   &  Co. 


SWEETENED  CONDENSED  MILK — CONDENSING  67 

in  the  pan  is  very  small,  making  possible  the  operation  of  the  lower 
coils  independent  of  the  upper  coils  and  thereby  avoiding  the  danger 
of  burning  the  milk,  which  inevitably  occurs  when  the  heated  coils 
are  not  completely  submerged.  This  arrangement  increases  the 
heating  efficiency  of  the  pan,  heat  can  be  turned  on  the  lowest  coil 
almost  immediately  after  starting  operation,  and  toward  the  end 
of  the  batch,  when  the  milk  again  boils  low,  some  of  the  coils  are 
still  covered  and  can  be  used.  The  shorter  length  of  these  coils 
from  inlet  to  exhaust  also  makes  possible  the  simultaneous  utilization 
of  a  greater  volume  of  steam.  These  combined  features  materially 
increase  the  rapidity  of  evaporation  and  augment  the  capacity  of  the 
pan.  These  improved  coils  have  the  further  advantage  that  their 
exhausts  do  not  have  to  be  carried  through  the  jacket,  but  pass 
through  the  body  of  the  pan. 

Jacket  and  coils  are  connected  independently  with  the  direct 
steam  main  from  the  boiler.  Each  connection  at  the  pan  should 
carry  a  valve  and  a  steam  gauge  on  the  pan-side  of  the  valve.  The 
main  steam  line  and  connections  leading  to  pan  should  be  properly 
insulated  by  proper  pipe  coverings,  in  order  to  supply  the  pan  with 
as  dry  steam  as  possible. 

The  drips  or  discharge  ends  of  the  jacket  and  coils  are  con- 
nected with  the  boiler  feed  water  tank.  If  the  pan  has  sufficient 
heating  surface  and  is  operated  properly,  the  drip  ends  of  the  jacket 
and  coils  should  discharge  warm  water  only,  and  not  free  steam. 
The  jacket  and  coils  should  be  free  at  the  drip  or  discharge  ends 
so  that  all  condensation  water  may  be  quickly  and  continuously 
removed.  This  is  necessary  in  order  to  make  the  most  economical 
use  of  the  steam  and  to  secure  high  efficiency  of  evaporation.  In 
order  to  guard  against  back  pressure  the  drips  may  be  equipped 
with  suitable  check  valves. 

Through  the  walls  of  the  body  of  the  pan  also  enters  the  milk 
draw  pipe.  This  pipe  connects  with  the  hot  well  and  through  it  the 
milk  rushes  into  the  pan.  Immediately  outside  of  the  pan  the  milk 
pipe  should  be  equipped  with  a  valve  to  regulate  the  inflow.  The 
size  of  the  milk  draw  pipe  and  valve  is  governed  by  the  capacity  of 
the  pan ;  usually  two  to  three  inches  in  diameter.  Inside  of  the  pan 
the  milk  pipe  should  be  turned  down.  If  this  provision  is  not  made, 
the  milk  shoots  straight  across  the  pan  atomizing  into  a  dense  spray, 
which  is  partly  drawn  over  into  the  condenser,  causing  loss  of  milk. 


68 


D  CONDENSED  MILK — CONDENSING 


THE  DOME:  rests  on  top  of  the  body  of  the  pan.  It  is  equipped 
with  a  manhole,  manhole  cover,  thermometer,  vacuum  gauge,  sight 
glasses,  lights  and  blow-down  valve,  or  vacuum  breaker.  The 
manhole  measures  about  fourteen 
to  eighteen  inches  in  diameter.  It  is 
closed  by  a  solid  brass  cover  with 
a  well-fitting,  ground  surface  flange. 
The  cover  carries  a  five-inch  eye- 
glass or  sight-glass  through  which 
the  operator  watches  the  boiling 
milk  in  the  pan.  The  stem  of  the 
thermometer  is  enclosed  in  a  brass 
casing  and  reaches  to  near  the  bot- 
tom of  .the  pan.  Some  processors 
prefer  a  short  thermometer  which  Fig.  17.  vacuum  gauge 

registers  the  temperature  of  the  va-  courtesy  of  Arthur  Harris  &  Co. 
pors  instead  of  that  of  the  milk.  As  both,  the  milk  and  the  vapors  are 
subjected  to  the  same  pressure,  their  respective  temperatures  are  the 
same.  The  long-stem  thermometer,  the  bulb  of  which 
is  submerged  in  the  milk,  however,  is  more  sensitive 
and  registers  changes  in  temperature  more  rapidly, 
because  the  milk  is  a  better  conductor  of  heat  than 
the  vapors.  The  vacuum  gauge  connects  with  the 
interior  of  the  pan,  and  indicates  the  number  of 
inches  of  vacuum.  A  mercury  column  may  be  used 
in  the  place  of  the  vacuum  gauge.  In  the  rear  of 
the  dome  there  are  two  sight  glasses.  Through  these 
the  interior  of  the  pan  is  illuminated  by  means  of 
lamps,  gas  or  electric  lights.  The  "blow-down" 
valve,  or  vacuum  breaker,  serves  to  admit  air  into 
the  pan  in  order  to  "break"  the  vacuum.  This  is 
Fig.  18.  necessary  for  readily  drawing  off  the  finished  con- 

Thermometer       densed  milk.     It  is   further  needed  to  prevent  the 

for  vacuum  pan 

Courtesy  of        contents  of  the  vacuum  pan  from  being  drawn  over 
Arth&rc?arriS    *nto  tne  conQlenser,  whenever  the  milk  rises  above  a 
safe  level. 

A  further  accessory  of  the  dome  may  be  an  automatic  milk 
sampler.  The  sampler  tube  is  carried  through  the  wall  of  the  dome 
and  extends  to  near  the  bottom  inside  of  the  pan.  Where  this  tube 


SWEETENED  CONDENSED  MILK — CONDENSING 


69 


projects  through  the  dome  it  is  equipped  with  motor,  pump,  piston, 
striking  cup  and  hydrometer.  The  striking  cup  at  its  upper  end 
terminates  in  a  small  chamber  equipped  with  a  sight-glass  through 
which  the  operator  notes  the  position  of  the  hydrometer. 

The  Condenser. — The  condenser 
is  that  portion  of  the  condensing  ap- 
paratus in  which  the  vapors,  rising 
from  the  boiling  milk  in  the  pan,  are 
condensed  to  water.  The  condenser 
is  attached  to  the  dome  of  the^  pan. 
There  are  three  types  of  condensers  in 
use,  the  surface  condenser,  the  baro- 
metric condenser  and  the  wet-vacuum 
spray  condenser. 


Fig.  19.     Vacuum  breaker  or  blow- 
down   valve 
Courtesy  Arthur  Harris  &  Co. 

THE  SURFACE  CONDENSER  consists 
of  a  tube  cylinder  filled  with  brass 
tubes,  mounted  on  a  receiver.  The 
water  used  for  cooling  circulates  out- 
side of  the  tubes  and  the  vapors  pass 
through  the  tubes,  where  they  are 
chilled  and  condensed.  This  conden- 
ser has  the  advantage  of  enabling  the 
operator  to  note  the  amount  of  con- 
densation and  to  measure  the  amount 
of  water  actually  condensed.  The  re- 
ceiver at  the  bottom  of  the  condenser 
should  be  so  arranged  that  it  can  be 
drained  at  will  and  without  interfer- 
ing with  or  retarding  the  operation  of 
the  pan. 

THE  BAROMETRIC  CONDENSER  con- 


Fig.  20.     The  surface  condenser 


sists  of  a  vertical  cylinder  of  iron  or   CourteJLc°h 


chine 


70 


SWEETENED  CONDENSED  MILK — CONDENSING 


brass,  equipped  with  a  spray  jet,  through  which  the  cooling  water 
enters  the  condenser.  The  vapors  being  drawn  over  from  the  vio- 
lently boiling  milk  in  the  pan,  are  condensed  by  passing  through  this 
spray  of  cold  water.  This  condenser  discharges  its  water  into  a 


Fig.  21, 


Vacuum   pan   with   dry  vacuum   barometric  condenser 
Courtesy  of  Arthur  Harris  &  Co. 


tight  cistern  in  the  ground.  The  condenser  is  placed  so  that  its  bot- 
tom flange  is  about  thirty-five  feet  above  the  water  level  of  the  cis- 
tern in  which  the  discharge  pipe  from  the  condenser  terminates.  The 
height  of  the  condenser  depends  on  the  barometric  pressure  of  the 
location  where  it  is  installed-  The  lower  the  altitude  and,  therefore, 
the  higher  the  atmospheric  pressure,  the  higher  must  the  condenser 


SWEETENED  CONDENSED  Miuc — CONDENSING  71 

be  above  the  cistern.  At  the  sea  level,  the  atmospheric  pressure  sus- 
tains a  water  column  about  thirty-four  feet  high.  This  water  column 
in  the  discharge  pipe  seals  the  vacuum  and  at  the  same  time  permits 
the  water  from  the  .spray  and  the  condensation  water  to  escape  auto- 
matically. The  cistern  in  which  the  water  column  terminates  should 
be  of  sufficient  size  to  hold  about  one-third  more  water  than  the  ca- 
pacity of  the  entire  length  of  the  discharge  pipe  calls  for  and  should 
have  a  large  overflow  into  the  sewer.  When  the  pan  is  in  operation 
and  a  uniform  vacuum  is  maintained,  the  level  of  the  water  column 
remains  constant  and  the  excess  water  from  the  condenser  over- 
flows from  the  cistern  into  the  sewer. 


Fig.   22.     The   wet-vacuum    spray 

condenser 
Courtesy  of  Arthur  Harris  &  Co. 


THE  WET- VACUUM  SPRAY  CONDENSER  consists  of  a  huge  hol- 
low cylinder  of  brass  or  iron,  usually,  but  not  necessarily,  horizontal. 

The  horizontal  spray  condensers  are  usually  equipped  with  a 
perforated  spray  pipe,  placed  lengthwise  in  the  cylinder.  This  spray 
pipe  should  run  close  to  the  top  side  of  the  cylinder,  so  as  to  give 
the  spray  that  escapes  from  the  holes  on  the  upper  side  of  the  spray 
pipe  a  chance  to  strike  the  top  of  the  horizontal  cylinder  with  force 
and  to  become  atomized.  The  spray  pipe  connects  at  the  end  nearest 
the  pan  with  the  pipe  supplying  the  cooling  water.  When  the  pan 
is  in  operation,  a  shower  of  cold  water  issues  forth  from  the  per- 
forations of  the  spray  pipe  as  the  result  of  the  reduced  pressure  in 
pan  and  condenser.  The  force  with  which  the  water  escapes  these 
perforations  is  further  augmented  by  the  fact  that  in  most  cases 
the  water  supply  tank  is  located  higher  than  the  condenser.  The 
hot  vapors  arising  from  the  boiling  milk  in  the  pan  are  drawn  over 
into  the  condenser,  where  they  come  in  contact  with  the  cold  water 
spray  and  are  condensed.  The  bottom  of  the  condenser  cylinder, 
at  the  end  farthest  from  the  pan  is  connected  with  the  suction  end 


72  SWEETENED  CONDENSED  MILK — CONDENSING 

of  the  vacuum  pump  through  which  the  water  and  the  condensed 
vapors  in  the  condenser  escape. 

In  the  vertical  spray  condenser  the  condenser  cylinder  is  up- 
right, located  either  on  top  of  the  pan  or  at  some  distance,  as  is  the 
case,  for  instance,  where  a  catch-all  is  installed  between  pan  and 
condenser.  The  interior  arrangement  of  the  vertical  condenser 
varies  somewhat  with  the  different  makes.  The  vertical  condenser 
most  widely  used  in  American  condenseries  consists  of  a  double 
insulated  vapor  tube  setting  on  top  of  the  pan.  This  insulated  tube 
is  surrounded  by  and  connects  with  a  spray  chamber,  which  termi- 
nates at  its  top  in  a  perforated  metal  plate  and  which  has  an  open- 
ing in  the  side  near  the  bottom  that  connects  with  the  vacuum  pump 
supplying  the  suction  and  that  permits  the  escape  of  the  condensed 
vapors  and  cooling  water.  The  cooling  water  enters  at  the  top  of 
the  condenser.  Immediately  underneath  the  water  inlet  it  strikes 
a  metal  cone  or  disc  which  prevents  the  water  from  running  into 
the  vapor  tube,  and  distributes  it  evenly  over  the  perforated  spray 
plate.  The  vapor  rises  into  the  vapor  tube  of  the  condenser  and  is 
drawn  over  into  the  spray  chamber  surrounding  it,  where  the 
vapor  is  condensed  by  the  spray  of  water  issuing  from  the  per- 
forated spray  plate  which  tops  the  spray  chamber  and  which  con- 
tains a  large  number  of  very  small  holes.  As  the  water  falls 
through  these  openings  by  gravity,  the  spray  is  uniform  and  con- 
stant and  does  not  depend  on  the  amount  of  water  used,  nor  does 
it  require  water  pressure  on  the  condenser. 

The  chief  difference  between  the  wet-vacuum  condenser  and 
the  barometric  condenser  is  that  in  the  wet-vacuum  condenser  the 
water  from  the  condenser  passes  through  the  vacuum  pump,  while 
in  the  barometric  condenser  the  water  does  not  pass  through  the 
vacuum  pump,  but  goes  direct  into  the  sewer  and  the  vacuum  is 
sealed  by  the  barometric  water  column.  So  far  as  practical  experi- 
ence has  shown,  there  is  no  material  difference  in  the  efficiency  be- 
tween these  two  types  of  condensers.  The  water  column  of  the 
barometric  condenser  helps  somewhat  to  maintain  a  uniform  vacuum. 
It  necessitates,  however,  the  installation  of  the  pan  inconveniently 
high  and  requires  somewhat  more  expensive  machinery  than  is  the 
case  with  the  wet-vacuum  condenser.  The  chief  difference  between 


SWEETENED  CONDENSED  MILK — CONDENSING  73 

both  of  these  systems  and  the  surface  condenser  is  that,  in  the  wet- 
vacuum  and  barometric  condensers  the  condensed  vapors  mix  with 
the  cooling  water,  while  in  the  surface  condenser  the  condensed  va- 
pors are  collected  and  carried  off  separately  and  without  mixing  with 
the  cooling  water.  In  the  case  of  condensing  liquids,  the  vapors  of 
which  are  of  commercial  value,  the  surface  condenser  must  be 
used.  The  surface  condenser,  however,  is  of  relatively  small  ca- 
pacity and  the  cooling  water  cannot  be  utilized  as  economically  as 
in  the  case  of  the  other  systems.  Where  large  quantities  of  vapors 
are  to  be  handled  and  the  vapors  have  no  commercial  value,  as  is 
the  case  in  condensing  milk,  the  barometric  and  wet-vacuum  con- 
densers are  best  suited ;  their  operation  utilizes  the  cooling  water 
most  economically. 

CARE  OF  THE  CONDENSER. — In  the  operation  of  the  spray  and 
jet  condenser,  special  attention  should  be  paid  to  the  condition  of 
the  spray  pipe,  or  spray  plate.  Especially,  when  the  water  used  con- 
tains much  organic  matter,  as  is  the  case  with  water  from  a  creek, 
pond  or  lake,  there  is  a  tendency  of  the  spray  pipe  becoming  filled 
and  coated  with  slimy  organic  matter,  causing  the  perforations  to 
clog.  This  renders  the  distribution  of  the  spray  irregular  and  the 
control  of  the  pan  difficult.  It  causes  great  waste  of  water  because 
much  of  the  water  is  discharged  from  the  condenser  and  lost  without 
coming  into  direct  contact  with  the  vapors.  The  water  is,  therefore, 
not  utilized  economically  and  the  difference  between  the  temperature 
of  the  vapors  and  the  discharge  of  the  condenser  is  excessive.  In 
order  to  avoid  this  the  condenser  should  be  cleaned  out  thoroughly 
at  least  once  a  week,  or  oftener  if  necessary,  to  keep  the  pores  of  the 
spray  pipe  free  from  obstructions.  It  is  advisable  to  install  con- 
densers equipped  with  a  manhole  on  top  or  at  the  end,  otherwise 
access  to  the  spray  pipe  is  not  sufficiently  convenient  to  insure  fre- 
quent inspection  and  thorough  cleaning  by  the  average  operator. 

The  Expansion  Tank,  Catch- All,  or  Milk  Trap.— T  his  is  a 

tank  frequently  installed  between  the  dome  of  the  pan  and  the  con- 
denser. Its  purpose  is  to  collect  and  reclaim  any  milk  that  may  be 
carried  over  from  the  pan  and  to  prevent  its  escape  and  loss  through 
the  condenser. 


74 


SWEETENED  CONDENSED  MILK — CONDENSING 


Fig.  23. 


Vacuum  pan  with  milk 
trap 

Courtesy  of  Arthur  Harris  &  Co. 


If  the  pipe  through  which  the  milk  enters  the  pan  is  turned 
down  and  its  end  is  carried  to  near  the  bottom  of  the  pan,  so  as  to 

avoid  the  formation  of  excessive 
milk  spray,  if  the  pan  is  operated 
carefully  and  if  the  milk  is  kept  at 
a  reasonably  low  level,  there  is  very 
little  danger  of  milk  being  carried 
over  into  the  condenser  in  quantities 
sufficient  to  be  of  any  consequence. 
Under  these  conditions  the  installa- 
tion of  a  special  milk  trap  between 
the  pan  and  the  condenser  for  the 
purpose  of  collecting  the  escaping 
milk  spray  and  carrying  it  back  to 
the  pan  is,  therefore,  an  unnecessary 
expense. 

If  the  pan  is  small  in  comparison  to  the  amount  of  milk  to  be 
condensed,  and  if  it  is  forced  beyond  its  intended  capacity  so  that 
the  milk  boils  up  high,  there  usually  is  considerable  loss  of  milk,  as 
indicated  by  the  foaminess  and  milky  color  of  the  exhaust  of  the 
vacuum  pump.  In  such  cases  the  mechanical  loss  of  an  average 
size  batch  may  amount  to  several  hundred  pounds  of  milk.  In 
order  to  not  lose  this  milk,  a  milk-trap  or  catch-all  may  be  installed 
between  the  pan  and  the  condenser.  The  vapors  loaded  with  the 
milk  spray  enter  the  trap  near  the  top.  The  spray  drops  to  the  bot- 
tom of  the  trap,  while  the  vapors  are  drawn  over  into  the  condenser, 
where  they  are  condensed  as  usual.  This  trap  may  be  constructed 
of  sufficient  size  so  as  to  serve  as  a  reservoir  to  collect  all  the  milk 
that  is  carried  over,  and  at  the  conclusion  of  the  process  the  con- 
tents of  the  trap  are  drawn  from  the  bottom  and  are  condensed  with 
the  next  batch ;  or  the  bottom  of  the  trap  may  be  connected  with  the 
pan  so  that  the  milk  thus  carried  over  flows  back  into  the  pan  auto- 
matically. In  this  case  a  small  trap  only  is  necessary. 

It  should  be  understood  that  the  milk  trap  is  only  a  remedy  and 
not  a  preventive.  Where  the  capacity  of  the  pan  is  in  proportion 
to  the  amount  of  milk  to  be  condensed,  as  it  should  be,  and  where 
the  pan  is  operated  properly,  the  trap  is  unnecessary.  The  trap  is 
an  additional  piece  of  apparatus  to  be  kept  clean.  Unless  it  is  so 
constructed  that  access  can  be  had  to  all  parts  of  its  interior  and 


CONDENSED  MILK — CONDENSING  75 

unless  it  really  is  kept  clean  at  all  times,  it  may  become  a  serious 
source  of  contamination. 

The  Vacuum  Pump. — The  vacuum  pump  is,  strictly  speaking, 
not  a  part  of  the  vacuum  pan,  but  its  intimate  connection  with  the 
pan  makes  it  necessary  to  briefly 
consider  it  at  this  point.  The 
suction  end  of  the  vacuum 
pump  is  connected  with  the  end 
of  the  condenser  farthest  from 
the  pan.  The  vacuum  pump 
exhausts  the  pan,  forming  a 
partial  vacuum.  There  are  prin- 
cipally  two  types  of  vacuum 
pumps  used  in  the  milk  con- 
densery,  the  dry-vacuum  pump  and  the  wet-vacuum  pump.  The 
dry-vacuum  pump  is  used  in  the  factories  with  the  dry-vacuum 
system,  i.  e.,  where  the  cooling  water  and  the  condensation  water 
escape  to  the  sewer  direct  and  without  passing  through  the  vacuum 
pump,  as  is  the  case  with  the  surface  condenser  and  the  barometric 
condenser.  The  wet-vacuum  pumps  are  used  with  the  wet-vacuum 
system,  where  the  cooling  water  and  the  condensation  water  pass 
through  the  cylinder  of  the  pump.  The  dry-vacuum  pumps  have 
the  advantage  of  permitting  the  operation  of  the  machine  at  a 
higher  piston  speed  than  the  wet-vacuum  pumps  in  which  the  water 
must  be  displaced  at  the  end  of  each  stroke.  The  cylinders  of  the 
dry- vacuum  pump  are  cooled  by  water  jackets.  The  initial  cost  of 
the  dry-vacuum  pumps,  however,  is  greater  than  that  of  the  wet- 
vacuum  pumps. 

The  efficiency  of  the  vacuum  apparatus  depends  very  largely 
on  the  vacuum  pump.  Rapid  evaporation  at  a  relatively  low  tem- 
perature necessitates  the  maintenance  of  a  high  vacuum.  The  type, 
material,  construction,  workmanship,  installation  and  operation  of 
the  vacuum  pump  should  be  such  as  to  insure  the  maximum  effic- 
iency. 

The  pump  should  be  placed  on  a  good  foundation  and  as  near 
the  vacuum  pan  as  practicable  in  order  that  the  full  benefit  of  the 
vacuum  may  be  realized.  The  suction  pipe  and  all  connections  must 
be  tight.  The  suction  pipe  must  be  of  the  size  directed  by  the  man- 


76 


SWEETENED  CONDENSED  MILK — CONDENSING 


ufacturer,  as  short  as  possible  and  with  few  and  easy  bends.  The 
grade  of  the  suction  pipe  should  be  uniform  in  order  to  avoid  air 
pockets. 


Fig.  25.     Dry-vacuum   pump 

Courtesy  of  Buffalo  Foundry  &  Machine  Company 

The  water  should  be  turned  into  the  condenser  before  the 
vacuum  pump  is  started.  The  pump  should  not  run  at  a  higher 
speed  than  is  necessary  to  secure  the  required  vacuum.  Excessive 
speed  means  high  steam  consumption  and  heavy  wear  and  tear  on 
the  pump.  The  amount  of  water  supplied  to  the  condenser  should 
be  regulated  to  suit  the  requirements.  Ordinarily,  and  with  a 
vacuum  of  twenty-five  to  twenty-six  inches,  the  temperature  of  the 
condenser  discharge  should  be  about  110  degrees  F.  A  lower  tem- 
perature would  cause  excessive  and  uneconomic  use  of  water.  The 
basin  on  the  vacuum  cylinder  should  be  kept  filled  with  water  to 
prevent  admission  of  air  to  the  cylinder  through  the  stuffing  box, 
and  the  spray  pipe  or  jet  in  the  condenser  should  be  inspected  often 
to  make  sure  that  the  perforations  are  not  clogged.  The  stuffing 
box  of  the  cylinder  should  be  well  packed  with  a  good  quality  of 
packing  and  the  steam  cylinder  well  oiled.  Start  the  pump  slowly. 
Belt-driven  pumps,  especially  those  equipped  with  a  fly-wheel,  insure 
greater  uniformity  of  speed  than  direct-acting,  steam-driven  pumps. 
Steam-driven  pumps  should  be  furnished  with  a  high  grade  gov- 
ernor. The  vacuum  pump  should  have  a  capacity  proportionate  to 
the  size  of  the  vacuum  pan,  amount  of  heating  surface,  steam  pres- 
sure and  temperature  of  condensing  water. 

Science  and  Practice  of  Evaporating  in  Vacuo. — PURPOSE  OF 
CONDENSING  IN  VACUO. — The  important  advantages  gained  by  evap- 


SWEETENED  CONDENSED  MILK — CONDENSING  77 

orating  milk  under  reduced  pressure,  or  in  vacuo,  are :  economy  of 
evaporation,  rapidity  of  evaporation,  low  temperature  and  large 
capacity  of  apparatus.  All  of  these  features  are  essential  in  the  suc- 
cessful condensing  of  milk. 

Rapid  evaporation  cannot  take  place  until  the  milk  is  brought 
to  the  boiling  point  and  is  kept  there  until  evaporation  is  completed. 
Under  atmospheric  pressure  and  at  the  seal  level,  the  boiling  point 
of  water  is  212  degrees  F.,  the  boiling  point  of  milk  is  very  slightly 
higher,  about  214  degrees  F.  Evaporating  of  milk  under  atmos- 
pheric pressure  in  an  open  kettle,  however,  is  a  relatively  slow 
process,  requiring  a  long  time,  much  fuel  and  large  apparatus.  Fur- 
thermore, exposure  of  the  milk  to  212  to  214  degrees  F.  long  enough 
to  complete  evaporation  would  render  the  product  unsuitable  for 
market.  The  properties  of  some  of  its  ingredients  are  altered,  the 
product  would  assume  a  dark  color  and  a  marked  cooked  flavor  as 
the  result  of  the  effect  of  heat.  All  of  these  objections  are  mini- 
mized and  partly  avoided  by  lowering  the  boiling  point  of  milk. 
These  objections,  however,  do  not  apply  to  evaporation  under  atmos- 
pheric pressure  by  film  treatment,  as  is  the  case  with  the  Continuous 
Concentrator  described  in  Chapter  XIV,  page  133. 

RELATION  OF  PRESSURE  TO  BOILING  POINT. — The  temperature 
at  which  milk  boils  depends  on  the  pressure  to  which  it  is  exposed. 


78 


SWIFTENED  CONDENSED  MILK — CONDENSING 


The  table  below  shows  the  boiling  point  of  water  at  pressures 
ranging  from  atmospheric  pressure  at  the  sea  level  (14.72  pounds 
per  square  inch)  to  a  complete  vacuum. 


BOILING  POINTS  OF  WATER  AT  DIFFERENT  VACUA. 


Absolute  pres- 
sure per 
square  inch 

Vacuum  inches 
of  mercury 
column 

Vacuum    milli- 
meters 
of  mercury 
column 

Temperatures 
of   boiling 
point   of 
water,  F. 

Temperatures 
of   boiling 
point   of 
water,  C. 

14.720 

0.00 

00 

212.00 

100.00 

14.010 

1.42 

36 

209.55 

98.5 

13.015 

3.45 

88 

205.87 

96.8 

12.015 

5.49 

139 

201.96 

94.3 

11.020 

7.52 

191 

197.75 

91.9 

10.020 

9.56 

243 

193.22 

89.5 

9.020 

11.60 

295 

188.27 

86.75 

8.024 

13.63 

346 

182.86 

83.7 

7.024 

15.67 

398 

176.85 

80.5 

6.024 

17.70 

450 

170.06 

76.8 

5.029 

19.74 

502 

162.28 

72.5 

4.029 

21.78 

553 

153.01 

67.2 

3.034 

23.81 

605 

141.52 

60.8 

2.034 

25.85 

657 

126.15 

52.3 

1.040 

27.88 

708 

101.83 

38.7 

.980 

28.00 

712 

100.00 

37.8 

.735 

28.50 

724 

90.00 

32.2 

.544 

28.89 

734 

80.00 

26.7 

.402 

29.18 

741 

70.00 

21.1 

.294 

29.40 

747 

60.00 

15.6 

.216 

29.56 

751 

50.00 

10.0 

.162 

29.67 

754 

40.00 

4.4 

.127 

29.74 

756 

32.00 

1  By  courtesy  of  the  Buffalo  Foundry  &  Machine  Company. 


CONDENSED  MILK — CONDENSING  79 

The  pressure  or,  correctly  speaking,  the  vacuum,  is  expressed 
in  terms  of  inches  of  mercury  which  the  atmospheric  pressure  sus- 
tains. The  mercury  column  is  not  a  direct  measure  of  the  pres- 
sure, but  it  shows  the  difference  between  the  atmospheric  pressure 
and  the  absolute  pressure  in  the  vacuum  chamber.  The  atmospheric 
pressure  at  the  sea  level  is  14.7  pounds  per  square  inch.  It  sus- 
tains a  mercury  column  in  an  absolute  vacuum  of  30  inches  at  62 
degrees  F.,  and  of  29.922  inches  at  32  degrees  F.  The  absolute 
vacuum  may  be  calculated  by  multiplying  the  atmospheric  pressure 
by  the  factor  2.04.  In  case  there  is  only  a  partial  vacuum  the 
mercury  column  sustained  is  lowered  to  the  extent  of  the  absolute 
pressure  in  the  vacuum  pan.  The  absolute  pressure  may  be  calcu- 
lated as  follows : 

AV  =  Absolute  vacuum   which  is  thirty   inches  at  the 

sea  level. 

V  ==  Actual  vacuum. 
P  =  Atmospheric  pressure  which   is   14.7  pounds  at 

the  sea  level. 
AP  =  Absolute  pressure. 

Example:  The  actual  vacuum  in  the  pan  is  25  inches  at  the 
sea  level.  What  is  the  absolute  pressure? 

PX  (AV  — V)     14. 7  X  (30  —  25) 

; = =  2.45    pounds    of    absolute 

pressure  per  sq.  inch. 

RELATION  OF  ALTITUDE  TO  ATMOSPHERIC  PRESSURE. — At  alti- 
tudes higher  than  the  sea  level,  the  atmospheric  pressure  is  reduced 
and  the  mercury  column  is  lowered,  though  the  absolute  pressure 
in  the  vacuum  pan  may  be  the  same.  Therefore,  in  factories  lo- 
cated at  high  altitudes  the  mercury  column  will  show  fewer  inches 
of  vacuum  at  a  given  temperature  and  with  a  given  absolute 
pressure. 

The  following  table  shows  the  barometric  reading  in  inches  of 
mercury  column  and  the  atmospheric  pressure  in  pounds  per  square 
inch  at  different  altitudes: 


80 


SWEETENED  CONDENSED  MILK — CONDENSING 


1  BAROMETRIC  READING  CORRESPONDING  WITH  DIFFERENT 
ALTITUDES. 


Barometric 
reading  in 
inches  of 
mercury 

Atmospheric 
pressure  in 
pounds  per 
square  inch 

Altitude 
above  sea 
level   in   feet 

Barometric 
reading   in 
inches  of 
mercury 

Atmospheric 
pressure  in 
pounds  per 
square   inch 

Altitude 
above  sea 
level 
in  feet 

30.0 

14.72 

0 

23.5 

11.54 

6412 

29.7 

14.60 

264 

23.0 

11.30 

6977 

29.5 

14.47 

441 

22.5 

11.05 

7554 

29.2 

14.35 

710 

22.0 

10.80 

8144 

29.0 

14.23 

890 

21.5 

10.56 

8747 

28.7 

14.11 

1163 

21.0 

10.31 

9366 

28.5 

13.98 

1347 

20.0 

9.81 

10648 

28.2 

13.86 

1625 

19.0 

9.32 

11994 

28.0 

13.74 

1812 

18.0 

8.82 

13413 

27.5 

13.50 

2285 

17.0 

8.33 

14914 

27.0 

13.26 

2767 

16.0 

7.84 

16506 

26.5 

13.02 

3257 

15.0 

7.35 

18201 

26.0 

12.77 

3758 

14.0 

6.86 

19996 

25.5 

12.53 

4268 

13.0 

6.37 

21891 

25.0 

12.27 

4787 

12.0 

5.88 

23886 

24.5 

12.03 

5318 

11.0 

5.39 

25981 

24.0 

11.78 

5859 

1  By  courtesy  of  the  Buffalo  Foundry  &  Machine  Company. 


SWEETENED  CONDENSED  MILK — CONDENSING 


81 


In  the  following  table  may  be  found  the  altitudes  of  various 
cities  in  the  United  States: 

ALTITUDE  IN  FEET  OF  VARIOUS  CITIES  IN  THE 
UNITED  STATES. 

By  Courtesy  of  United  States  Department  of  Agriculture. 


Akron,  Ohio    940 

Albany,  N.  Y 22 

Atlanta,  Ga 1032 

Baltimore,  Md 92 

Birmingham,  Ala 600 

Boston,  Mass 16 

Buffalo,   N.   Y 583 

Burlington,  Vt 112 

Butte,  Mont 5555 

Charleston,  S.  C 12 

Chattanooga,  Tenn 672 

Chester,  Pa 22 

Chicago,  111 590 

Cincinnati,  Ohio   490 

Cleveland,  Ohio  582 

Dayton,  Ohio 740 

Denver,  Colo 5183 

Dallas,  Tex 430 

Des  Moines,  Iowa 805 

Detroit,  Mich 588 

Duluth,  Minn 609 

Houston,  Tex 46 

Indianapolis,  Ind 708 

Ithaca,  N.  Y 411 

Kansas  City,  Mo 750 

Knoxville,  Tenn 890 

Lexington,  Ky 955 

Little  Rock,  Ark 264 


Los  Angeles,  Cal 267 

Louisville,   Ky 453 

Memphis,  Tenn 256 

Milwaukee,   Wis 593 

Minneapolis,   Minn 812 

New  Haven,  Conn 10 

New  Orleans,   La 6 

New  York  City . , . .     54 

Oklahoma  City,  Okla 1197 

Omaha,  Neb 1016 

Philadelphia,  Pa 42 

Phoenix,  Ariz 1082 

Pittsburgh,  Pa 743 

Providence,  R.  1 11 

Richmond,  Va 51 

Rochester,  N.  Y 510 

St.  Louis,  Mo 455 

Salt  Lake  City,  Utah 4238 

San  Francisco,  Cal 15 

Santa  Fe,  N.  M 6952 

Seattle,  Wash 10 

South  Bend,  Ind 717 

Spokane,  Wash 1908 

Tampa,  Fla 15 

Washington,  D.  C 25 

Wichita,  Kan 1294 

Vicksburg,  Miss 1% 


82  SWEETENED  CONDENSED  MILK — CONDENSING 

According  to  Kent x  the  relation  of  altitude  to  atmospheric 
pressure  per  square  inch  is  as  follows : 

Pounds  Pressure 

Altitude  Per  Square  Inch 

At  sea  level  -       14.7 

Y^  mile  above  sea  level  -       14.02 

J/2  mile  above  sea  level  -       13.33 

%  mile  above  sea  level  -       12.66 

1  mile  above  sea  level  -       12.02 
1 Y^  miles  above  sea  level     -  -11.42 
\y2  miles  above  sea  level     -  -       10.88 

2  miles  above  sea  level     -  9.80 

"For  a  rough  approximation  we  may  assume  that  the  pressure 
decreases  one-half  pound  per  square  inch  for  every  1,000  feet  of 
ascent." 

The  absolute  pressure  in  the  pan  of  a  factory  located  at  Omaha, 
Neb.,  with  an  altitude  of  1,016  feet  above  sea  level,  and  condensing 
in  an  actual  vacuum  of  twenty-five  inches,  would  then  be  as  fol- 
lows : 

Atmospheric  pressure  —  14.7 —  .5  =  14.2  pounds  per  square 
inch. 

Absolute  vacuum  =  14.2  X  2.04  =  28.97  inches. 

14. 2  X  (28.97  —  25) 

Absolute  pressure  — 0     n>7 —  —  1.95  pounds 

^o.  y/ 

per  square  inch. 

RELATION  OF  STEAM  PRESSURE  IN  JACKET  AND  COILS,  WATER 
IN  CONDENSER,  TEMPERATURE  IN  PAN  AND  VACUUM,  TO  RAPIDITY 
OF  EVAPORATION. — The  temperature  of  the  vapors  in  the  vacuum 
pan  depends  directly  upon  the  pressure  or  vacuum  under  which 
they  are  generated.  The  more  nearly  complete  the  vacuum  and, 
therefore,  the  lower  the  pressure,  the  lower  the  temperature,  and, 
other  conditions  being  the  same,  the  more  rapid  the  evaporation. 
The  pressure  in  turn  is  governed  by  the  capacity  of  the  vacuum 
pump,  the  tightness  of  the  joints,  the  steam  pressure  in  jacket  and 
coils  and  the  amount  and  temperature  of  the  water  in  the  con- 
denser. 


1  Mechanical  Engineer's  Pocket-Book,  p.   581. 


NED  CONDENSED  MILK — CONDENSING  83 

With  a  low  capacity  vacuum  pump,  or  a  pump  running  irreg- 
ularly, or  too  slow,  or  too  fast,  and  with  leaky  joints,  the  vacuum 
will  always  be  low,  and  the  pressure  and  temperature  relatively  high. 
Under  these  conditions  the  pan  is  difficult  to  operate  and  evapora- 
tion is  slow. 

With  the  above  conditions  under  control  and  properly  adjusted, 
the  temperature  and  the  rapidity  of  evaporation  depend  on  the  steam 
pressure  in  the  jacket  and  coils  and  on  the  amount  and  temperature 
of  the  water  used  in  the  condenser. 

Twenty-five  pounds  of  steam  pressure  in  the  jacket  and  coils 
has  been  found  to  be  about  the  maximum  that  can  safely  be  used. 
With  this  steam  pressure  the  milk  coming  in  direct  contact  with 
the  heating  surface  is  exposed  to  about  267  degrees  F.  and  there  is 
a  tendency  for  some  of  it  to  bake  or  burn  on,  which  is  undesirable. 
The  walls  of  the  jacket  and  coils  are  also  subjected  to  considerable 
strain,  since  they  are  surrounded  by  an  almost  complete  vacuum. 
Then  again,  if  the  pan  has  the  proper  amount  of  heating  surface 
the  capacity  of  the  condenser  and  the  water  supply  are  in  most 
cases  insufficient  to  take  care  of  and  condense  the  vapors  arising 
from  the  boiling  milk  in  the  pan,  when  the  steam  pressure  in  jacket 
and  coils  approaches  or  exceeds  twenty-five  pounds..  Most  con- 
denseries  operate  their  pans  with  twelve  to  twenty  pounds  of  steam 
pressure  in  jacket  and  coils.  In  the  operation  of  some  pans  not 
more  than  about  five  pounds  steam  pressure  can  be  used  economically 
in  jacket  and  coils,  because  the  use  of  more  steam  causes  the  steam 
to  blow  through  and  out  of  the  coils.  This  may  be  due  to  relatively 
large  heating  surface,  or  small  evaporating  capacity  due  to  a  small 
capacity  pump  or  limited  water  supply  to  condenser. 

The  capacity  of  the  condenser  used  in  milk  condenseries  is 
very  largely  dependent  on  the  water  supply.  Whenever  the  con- 
denser is  forced  beyond  its  capacity,  by  using  excessive  steam  in 
jacket  and  coils,  the  vacuum  drops,  the  temperature  rises  and  the 
process  of  evaporation  is  retarded. 

The  higher  the  vacuum  the  more  rapid  the  evaporation.  A  rise 
in  the  steam  pressure  in  the  jacket  and  coils  increases  the  rapidity, 


84  SWEETENED  CONDENSED  MII^K — CONDENSING 

of  evaporation  only  as  long  as  enough  water  passes  through  the  con- 
denser to  maintain  a  high  vacuum.  As  soon  as  the  steam  pressure 
in  the  jacket  and  coils  reaches  the  point  where  the  water  in  the  con- 
denser fails  to  promptly  reduce  the  vapors,  the  vacuum  drops,  the 
temperature  in  the  pan  rises  and  evaporation  is  checked. 

The  condensing  of  milk  requires  immense  quantities  of  water ; 
experience  has  shown  that  it  takes  from  two  to  three  gallons  of 
water  to  condense  one  pound  of  fresh  milk.  The  water  supply  is 
one  of  the  weakest  links  in  most  condenseries,  so  that  economy  of 
water  is  one  of  the  important  factors  to  be  considered.  The  steam 
pressure  in  the  jacket  and  coils  should,  therefore,  be  so  regulated  as 
to  make  it  possible  to  maintain  the  maximum  vacuum  consistent 
with  reasonably  economic  use  of  water.  The  experience  of  the 
best  pan  operators  is  that  about  fifteen  pounds  of  steam  pressure  in 
the  jacket  and  coils  and  a  vacuum  of  twenty-five  inches  is  practic- 
ally the  maximum  that  can  be  maintained  under  average  conditions 
without  taxing  the  usual  water  supply  beyond  its  capacity.  With  a 
vacuum  of  twenty-five  inches  the  temperature  in  the  pan  is  about 
135  degrees  F.,  the  temperature  varying  somewhat  with  the  altitude 
of  the  factory.  In  some  condenseries  the  temperature  of  the  pan 
is  kept  at  150  degrees  F.  This  practice  may  economize  the  water 
a  trifle  better,  but  the  rapidity  of  evaporation  is  considerably  lower. 

Condensing  at  temperatures  lower  than  130  degrees  F.,  without 
reducing  the  steam  pressure  in  the  jacket  and  coils,  increases  the 
rapidity  of  evaporation,  but  taxes  the  water  supply  beyond  the  reach 
of  most  condenseries.  So  much  water  has  to  be  used  in  the  con- 
denser that  it  is  not  used  economically,  as  is  shown  by  the  relatively 
low  temperature  of  the  water  discharging  from  the  condenser.  The 
temperature  of  the  condenser  discharge  bears  a  direct  relation  to 
the  temperature  of  the  vapors  in  the  pan.  Observations  made  in 
various  factories  and  under  different  conditions  by  Hunziker  and 
others  showed  that  the  condenser  discharge  was  anywhere  from  5  to 
25  degrees  F.  lower  in  temperature  than  the  vapors  in  the  pan,  the 
difference  averaging  about  15  degrees  F. 

The  smaller  the  difference  in  temperature  between  the  con- 
denser discharge  and  the  vapors  in  the  pan,  the  more  economic  is 


SWEETENED  CONDENSED  MILK — CONDENSING  85 

the  use  of  the  water  and  vice  versa.  It  is  not  advisable  under  aver- 
age conditions  to  so  operate  the  pan  that  the  temperature  of  the 
condenser  discharge  drops  below  110  degrees  F.,  because  of  the 
wasteful  use  of  water  under  such  conditions. 

The  condensing  of  one  pound  of  milk  requires  about  one  pound 
of  steam  and  eighteen  to  twenty-five  pounds  of  water.  The  quan- 
tity of  heating  steam  used  for  condensing  in  vacuum  is  practically 
the  same  as  that  required  by  evaporating  in  open  pans.  In  order  to 
use  the  steam  economically  the  pan  should  be  so  operated  as  to  make 
possible  its  complete  condensation  by  the  time  it  leaves  the  jacket 
and  coils.  Whenever  so  much  steam  is  used  that  it  blows  through 
and  out  of  the  jacket  and  coils  without  being  condensed,  there  is 
great  waste  of  fuel.  For  further  details  on  this  point  see  "Descrip- 
tion of  the  Vacuum  Pan." 

Starting  the  Pan. —  Before  drawing  the  milk  into  the  pan,  the 
pan  should  be  thoroughly  rinsed  with  water,  then  steamed  until  the 
temperature  rises  to  about  180  degrees  F.  or  above.  Then  the  man- 
hole cover  is  put  in  place,  all  the  air  valves  are  closed,  water  is 
turned  into  the  condenser  and  the  vacuum  pump  is  started.  When 
the  vacuum  gauge  shows  over  twenty  inches  of  vacuum,  the  pan 
is  ready  for  the  milk. 

Operating  the  Pan.— The  valve  of  the  milk  pipe  leading  to  the 
pan  is  now  partly  opened.  The  milk  enters  the  pan  automatically 
as  the  result  of  the  reduced  pressure  in  the  pan.  When  the  milk 
covers  the  jacket,  steam  is  gradually  turned  into  the  jacket.  As 
each  coil  becomes  submerged  in  milk,  the  coils  are  charged  with 
steam.  At  no  time  should  steam  be  turned  on  the  jacket  and  coils 
when  they  are  not  completely  covered  with  milk,  as  such  action 
would  cause  the  milk  to  stick  to  and  burn  on  the  heating  surface, 
the  milk  would  assume  a  burnt  flavor,  it  would  become  permeated 
with  black  specks  and  the  evaporation  would  be  retarded.  On  the 
start,  but  a  few  pounds  of  steam  pressure  should  be  used  in  the 
jacket  and  coils,  to  avoid  burning,  owing  to  the  presence  in  the  milk 
of  considerable  air.  As  the  milk  becomes  more  concentrated  and 
settles  down  to  uniform  boiling,  the  steam  pressure  may  be  grad- 
ually increased  until  it  reaches  the  maximum.  The  maximum  pres- 


86  SWEETENED  CONDENSED  MILK — CONDENSING 

sure  permissible  must  be  governed  by  the  amount  of  heating  sur- 
face, the  capacity  of  the  vacuum  pump  and  the  temperature  and 
amount  of  water  available  for  use  in  the  condenser.  Under  aver- 
age conditions  about  fifteen  pounds  of  steam  pressure  may  be  safely 
used. 

During  the  early  stages  of  the  process,  when  the  milk  is  of 
low  density,  the  evaporative  duty  is  high,  probably  about  twenty- 
five  to  thirty-five  pounds  per  square  foot  of  heating  surface  with 
ten  pounds  of  steam  pressure.  This  gradually  decreases  and  is 
lowest  toward  the  end  of  the  process. 

When  enough  milk  is  in  the  pan  to  completely  cover  the  jacket 
and  coils,  the  milk  intake  should  be  reduced  and  regulated  in  ac- 
cordance with  the  rate  of  evaporation.  The  milk  is  drawn  into  the 
pan  continuously,  but  only  as  fast  as  it  evaporates.  It  should  be 
kept  as  much  as  possible  at  a  constant  level,  and  this  level  is  prefer- 
ably as  low  as  is  consistent  with  complete  covering  of  the  upper  coil. 

In  order  to  secure  maximum  rapidity  of  evaporation,  the 
vacuum  pump  should  run  at  the  proper  speed  and  its  operation 
should  be  uniform,  a  uniform  vacuum  and  temperature  should  be 
maintained  and  the  milk  should  be  prevented  from  rising  to  an  ab- 
normally high  level  in  the  pan. 

Prevention  of  Accidents. — The  operator  should  pay  strict  at- 
tention to  the  pan  in  order  to  avoid  loss  of  milk  due  to  accidents. 
He  should  watch  the  water  supply  and  govern  its  use  accordingly. 
If  the  water  supply  becomes  exhausted,  air  is  liable  to  be  drawn 
into  the  pan  through  the  condenser.  This  will  cause  the  milk  to  drop 
suddenly  and  then  rise  in  a  body,  threatening  to  escape  through  the 
condenser.  Whenever  air  in  considerable  quantities  is  allowed  to 
enter  the  pan  while  in  operation,  be  it  as  the  result  of  lack  of  water, 
or  through  any  other  cause,  or  when  the  vacuum  pump  is  allowed  to 
stop  and  live  steam  is  turned  into  the  milk  in  the  pan,  as  is  the  case 
when  the  milk  is  superheated,  the  escape  of  milk  may  be  avoided  by 
immediately  shutting  the  steam  inlet  to  the  jacket  and  coils,  by  clos- 
ing the  milk  intake  and  by  slightly  opening  the  blow-down  valve 
whenever  the  milk  rises  dangerously  high.  By  skillful  manipulation 
of  the  blow-down  valve  until  the  milk  again  settles  down  to  uniform 


CONDENSED  MILK — STRIKING  87 

boiling,  loss  can  be  avoided  and  the  process  can  be  continued  in  the 
normal  way. 

By  the  time  all  the  milk  is  in  the  pan,  condensation  is  nearly 
completed,  and  from  ten  to  twenty  minutes  further  boiling  usually 
gives  the  milk  the  desired  density.  Toward  the  end  of  the  process 
the  steam  pressure  in  jacket  and  coils  should  be  reduced  to  about 
five  pounds  or  less.  When  the  milk  approaches  the  desired  density, 
it  is  comparatively  heavy  and  viscous  and  boils  less  vigorously.  It 
therefore  is  more  directly  exposed  to  the  heating  surface.  In  the 
case  of  excessive  steam  pressure,  its  quality  is  jeopardized.  If  the 
batch  is  small  so  that  the  level  of  the  milk  drops  below  some  of  the 
coils,  steam  to  the  exposed  coils  should  be  turned  off  entirely. 

CHAPTER  VI. 
STRIKING  OR  FINISHING  THE  BATCH 

Definition. — When  the  boiling  milk  in  the  vacuum  pan  ap- 
proaches the  desired  degree  of  concentration,  the  batch  is  "struck." 
The  term  "striking"  is  applied  to  the  operation  of  sampling  the  con- 
densed milk  and  testing  the  sample  for  density.  This  term  very 
probably  referred,  originally,  to  the  meaning  of  "striking  the  batch 
right,"  that  is,  stopping  the  process  at  the  proper  time,  or  when 
the  milk  is  neither  too  thick  nor  too  thin.  It  then  expressed  the 
result  of  the  operation,  while  now  it  is  used  to  mean  the  operation 
itself. 

Ratio  of  Concentration, — Sweetened  condensed  milk  intended 
for  canned  goods  has  a  specific  gravity  of  1.28  to  1.30.  This  den- 
sity is  reached  usually  when  the  ratio  of  concentration  is  about 
2.5  :1,  i.  e.,  2.5  parts  of  fresh  milk  are  condensed  to  one  part  of  con- 
densed milk,  assuming  that  about  sixteen  pounds  of  sucrose  have 
been  added  to  every  one  hundred  pounds  of  fresh  milk. 

Occasionally  the  ratio  of  concentration  is  based  on  the  propor- 
tion of  water  evaporated,  in  which  case  it  is  obviously  much  higher 
than  when  based  on  the  amount  of  milk  required  to  make  one  pound 
of  condensed  milk,  because  the  added  cane  sugar  takes  the  place  of 


88  SWEETENED   CONDENSED  MII.K — STRIKING 

its  own  weight  of  water,  and  thereby  acts  as  a  diluent  of  the  con- 
densed milk.  Thus  let  us  assume  that  16  pounds  of  cane  sugar  are 
added  to  every  100  pounds  of  fresh  milk  and  that  it  takes  250  pounds 
of  fresh  milk  to  make  100  pounds  of  sweetened  condensed  milk., 
100  pounds  of  sweetened  condensed  milk,  therefore,  contain 
16  X  2.5  =40  pounds  of  cane  sugar.  Using  the  sugar-free  fin- 
ished product  as  the  basis  for  calculation,  then,  the  ratio  of  concen- 
tration would  be:  (1QQ-40)  =  4'17  to  L 

Instead  of  giving  the  ratio  of  concentration,  this  basis  of  calcu- 
lation determines  the  ratio  of  evaporation  only.  The  results  are. 
therefore,  erroneous  and  misleading.  It  does  not  materially  matter 
whether  the  diluent  in  the  condensed  milk  is  water  or  cane  sugar,  or 
both;  the  really  important  factor  is  the  per  cent  milk  solids  in  the 
condensed  milk  as  compared  with  the  per  cent  solids  in  the  original 
fresh  milk,  and  this  relation  is  solely  determined  by  the  amount  of 
fluid  milk  required  to  make  one  pound  of  condensed  milk,  or  by  the 
true  and  actual  ratio  of  concentration.  If  it  takes  2^  pounds  of 
fresh  milk  for  every  pound  of  condensed  milk,  then  the  ratio  of 
concentration  is  obviously  2.5  to  1  and  not  4.17  to  1. 

Methods. — To  know  just  when  the  proper  degree  of  concen- 
tration has  been  reached  is  difficult  and  requires  patience.  It  is 
here  where  the  processor  can  easily  make  or  lose  his  wages.  There 
are  various  indications  reminding  the  observant  processor  that  the 
milk  in  the  retort  is  nearly  "done,"  viz.,  time  consumed  for  con- 
densing, time  elapsed  since  all  the  milk  has  been  "drawn  up," 
amount  of  condensed  milk  left  in  the  pan  and,  most  of  all,  the  ap- 
pearance and  behavior  of  the  boiling  milk  itself.  Milk  that  has 
been  sufficiently  condensed  assumes  a  glossy,  glistening  lustre,  it 
boils  over  from  the  periphery  towards  the  center,  forming  a  small 
nucleus  or  puddle  of  foam  in  the  center  of  the  pan.  An  experienced 
and  observant  operator  knows  within  a  few  minutes  when  the  milk 
is  condensed  enough.  This  does  not  mean,  however,  that  he  should 
wait  until  the  last  minute  before  he  "strikes"  the  batch,  for  even 
the  most  skillful  and  experienced  processors  are  easily  deceived  by 
the  mere  appearance  of  the  condensed  milk  through  the  sight  glass. 


SWEETENED  CONDENSED  Miuc — STRIKING  89 

The  degree  of  concentration  may  be  more  accurately  determ- 
ined by  taking  a  sample  from  the  pan  and  testing  it  by  various 
methods,  such  as  by  weighing  a  definite  quantity  of  condensed  milk 
on  a  sensitive  scale,  by  the  use  of  a  resistance  apparatus,  or  by  the 
use  of  a  specially  constructed  hydrometer.  Of  these  the  Beaume 
hydrometer  has  been  found  the  most  suitable  to  use  under  average 
factory  conditions. 

Mechanical  devices  and  methods,  such  as  the  above,  can  be  de- 
pended upon,  when  all  the  conditions  influencing  the  specific  gravity 
of  the  liquid  are  under  control,  and  when  there  is  plenty  of  time 
for  their  manipulation.  When  the  boiling  and  rapidly  evaporating 
milk  in  the  retort  is  approaching  the  proper  density,  however,  quick 
action  is  essential.  One  minute  over-  or  under-condensing  may 
cause  the  milk  to  be  either  too  thick  or  too  thin  for  the  market  and 
may  necessitate  the  "re-running"  of  the  entire  batch.  These  instru- 
ments are,  therefore,  often  inadequate  at  the  time  they  are  needed 
most.  There  is  not  time  to  carefully  measure  and  weigh  out  a 
sample  of  sweetened  condensed  milk,  nor  can  the  processor  al- 
ways wait  until  the  hydrometer  has  found  its  equilibrium  in  as 
viscous  a  fluid  as  sweetened  condensed  milk.  Again,  the  density  or 
specific  gravity  of  the  finished  product  depends,  outside  of  the  de- 
gree of  concentration,  on  many  and  fluctuating  conditions,  such  as 
amount  of  heat  applied  toward  the  end  of  the  process,  the  tem- 
perature of  the  sample  when  drawn  and  the  per  cent  of  fat  and 
cane  sugar  in  the  condensed  milk.  It  is  for  these  reasons  that  arbi- 
trary mechanical  instruments  and  methods  are  not  uniformly  satis- 
factory and  are  liable  to  yield  misleading  results ;  while  they  are  very 
desirable  to  use  as  a  check,  the  experienced  eye  and  good  judgment 
of  the  processor  are  all  essential.  The  following  factory  methods 
have  been  found  satisfactory  and  reasonably  reliable : 

Draw  a  sample  from  the  pan  into  a  tin  dipper,  lower  the  dipper 
into  a  pail  of  ice  water  or  snow.  Stir  the  condensed  milk  with  a 
metal-back  thermometer  until  the  condensed  milk  is  cooled  to  70 
degrees  F.  Note  the  thickness  of  it.  Or,  finish  the  batch  at  a  con- 
stant temperature,  say  120  degrees  F.  Draw  a  sample  into  a  tin 
cup  and  note  the  thickness  by  examining  the  milk  when  pouring 


90 


SWEETENED   CONDENSED   MILK — STRIKING 


from  a  teaspoon.  The  transparency  of  the  milk  when 
thus  held  against  the  light  and  the  manner  in  which  the 
milk  piles  up  in  the  cup  furnish  a  practical  index  to 
its  density.  The  last  method  is  preferable  because  of 
its  greater  rapidity. 

USE  OF  BEAUME  HYDROMETER. — Beginners  and 
inexperienced  operators  do  well  to  take  numerous  sam- 
ples from  the  batch  in  the  operating  pan  and  to  start 
sampling  early,  so  as  to  avoid  over-condensing.  The 
use  of  a  Beaume  hydrometer,  especially  constructed 
for  sweetened  condensed  milk,  graduated  from  30  to 
37  degrees  B.  and  with  subdivisions  of  one-tenth  de- 
grees, is  an  additional  safeguard  to  insure  accuracy 
and  uniformity  of  thickness.  No  definite  figure  at 
which  the  Beaume  hydrometer  should  be  read  can  be 
stated  that  would  show  the  proper  density  under  all 
conditions.  The  Beaume  reading  of  sweetened  con- 
densed milk  of  the  proper  concentration  varies  with 
such  factors  as  per  cent  of  fat,  per  cent  of  sucrose 
and  per  cent  solids,  ratio  of  concentration  and  tem- 
perature of  the  condensed  milk  when  the  reading  is 
taken.  However,  for  general  guidance,  it  may  be 
stated  that  condensed  milk  of  proper  density,  made 
from  fresh  milk  of  average  richness  and  containing 
sucrose  at  the  ratio  of  sixteen  pounds  of  sugar  per 
one  hundred  pounds  of  fresh  milk,  will  show  a  Beaume 
reading  of  about  33.5  degrees  B.  at  60  degrees  F.,  or 
about  32  degrees  B.  at  120  degrees  F.  Sweetened  con- 
densed skim  milk  containing  approximately  40  per 
cent  sucrose  will  show  a  Beaume  reading  at  60  de- 
grees F.  of  about  37  degrees  B.,  or  about  35.5  degrees 
B.  at  120  degrees  F. 

CORRECTION  OF  HYDROMETER  READING  FOR  TEM- 
PERATURE.— The  Beaume  hydrometers  used  in  Ameri- 
can condenseries  are  graduated  to  give  correct  read- 
ings at  60  degrees  F.  If  the  readings  are  to  be  correct,  c- 


JHK 


Fig.  26. 
Beaume    hy- 
drometer   for 
sweetened 
condensed 

milk 
Courtesy 


CONDENSED  MILK — STRIKING  91 

or  if  it  is  desirable  to  convert  them  into  specific  gravity,  the  con- 
densed milk  should  have  a  temperature  of  60  degrees  F.  Where 
this  is  not  convenient,  the  observation  may  be  made  at  any  tem- 
perature convenient  and  the  reading  corrected  as  follows : 

When  the  temperature  is  above  60  degrees  F.  multiply  the  dif- 
ference between  the  observed  temperature  and  60  degrees  F.  by  the 
factor  .025  and  add  the  product  to  the  observed  reading  of  the 
Beaume  hydrometer.  When  the  temperature  of  the  observed  read- 
ing is  below  60  degrees  F.  the  corresponding  product  is  deducted. 

Example:  Beaume  reading  at  120  degrees  F.  is  31.2.  Cor- 
rected reading  is  31.2  +  [.025  X  (120  —  60)]  =  32.7. 

The  specific  gravity  may  be  calculated  when  the  Beaume  read- 
ing is  known,  by  using  the  following  formula : 

144  3 
Specific  gravity  =  J^ ;  B.  =  Beaume  reading 

Example:    Beaume  reading,  at  60  degrees  F.  is  33.1. 

144  -* 
Specific  gravity  =      m  3  _  33  t      =  1.2976 

In  the  following  table  are  assembled  figures  showing  the  spe- 
cific gravity  of  sweetened  condensed  milk  of  different  Beaume 
degrees,  varying  from  28  degrees  B.  to  37.8  degrees  B. 


92 


SWEETENED  CONDENSED  MII<K — STRIKING 


SPECIFIC  GRAVITY  OF  SWEETENED  CONDENSED  MILK  OF  DIFFERENT 

BEAUME  DEGREES 


Beaumg  at 
60  degrees  F. 

Specific 
Gravity 

Beaumg  at 
60  degrees  F. 

Specific 
Gravity 

28.0 

1.2407 

33.0 

1.2965 

.2 

1.2428 

.2 

1.2988 

,4 

1.2449 

.4 

1.3011 

.6 

1.2471 

.6 

1.3034 

.8 

1.2493 

.8 

1.3058 

29.0 

1.2515 

34.0 

1.3082 

.2 

1.2536 

.2 

1.3106 

.4 

1.2558 

.4 

1.3130 

.6 

1.2580 

.6 

1.3154 

.8 

1.2602 

.8 

1.3178 

30.0 

1.2624 

35.0 

.3202 

.2 

1.2646 

.2 

.3226 

.4 

1.2668 

.4 

.3250 

.6 

1.2690 

.6 

.3274 

.8 

1.2713 

.8 

.3299 

31.0 

1.2736 

36.0 

1.3324 

.2 

1.2758 

2 

1.3348 

.4 

1.2780 

.4 

1.3372 

.6 

1.2803 

.6 

1.3397 

.8 

1.2826 

.8 

1.3422 

32.0 

1.2849 

37.0 

1.3447 

.2 

1.2872 

.2 

1.3472 

.4 

1.2895 

.4 

1.3497 

.6 

1.2918 

.6 

1.3522 

.8 

1.2941 

.8 

1.3548 

CONDENSED   MILK — STRIKING 


93 


Sampling  of  Batch. — The  samples  can  be  drawn  from  the 
pan  by  operating  the  two  valves  at  the  bottom  explained  under 
"Description  of  Vacuum  Pan."  While  the  milk  is  condensing, 
the  partial  vacuum  in  the  pan  makes  impossible  the  drawing  off 
of  the  sample  by  simply  opening  the  outlet.  Instead  of  causing 
the  milk  to  come  out,  air  would  rush  in  with  violent  force  and 
would  cause  the  milk  in  the  pan  to  be  thrown  over  into  the  con- 


Fig.  27.     A  con- 
venient device 
for   sampling 
the   condensed 

milk  in  the  pan 

Courtesy  of 

Arthur  Harris 

&    Co. 


Fig.  28.     A  convenient  device  for  sampling 

condensed    milk   in   the   pan 
Courtesy  of  Arthur  Harris  &  Co. 


denser,  besides  dangerously  jolting  the  machinery.  For  this  reason 
the  outlet  is  equipped  with  two  valves,  both  of  which  are  closed  dur- 
ing the  condensing  process.  For  taking  samples,  open  the  upper 
valve.  This  allows  the  condensed  milk  to  run  into  the  nipple 
between  the  two  valves.  Now  close  the  upper  valve  and  open 
the  lower  one.  The  milk  will  run  out  freely.  The  first  sample 
should  be  rejected,  as  it  may  contain  water  caught  in  the  nipple. 

For  greater  convenience  and  increased  rapidity  of  sampling, 
especially  constructed  sample  testers  or  striking  cups,  attached 
to  the  side  of  the  body  of  the  pan  may  be  used.  The  latest  in- 


94  SWEETENED  CONDENSED  MILK — COOUNG 

vention  for  facilitating  the  sampling  and  striking"  is  the  automatic 
milk  striker  designed  by  Mojonnier  Bros.  Co.,  Chicago.  This 
ingenious  contrivance  consists  of  a  motor-driven  piston 
pump.  The  suction  tube  carrying  the  piston  extends  from 
the  dome  of  the  pan  into  the  boiling  milk.  This  tube  projects 
at  its  upper  end  through  the  wall  of  the  dome  and  over- 
flows into  a  hydrometer  cylinder.  This  cylinder  carries  at  its 
upper  end  a  chamber  permitting  unhindered  motion  of  the  hydro- 
meter and  the  end  of  this  chamber  which  faces  the  operator  is 
equipped  with  a  sight  glass  and  a  light.  In  the  cylinder  reposes 
a  Beaume  hydrometer.  Whenever  the  operator  desires  to  know 
the  density  of  the  condensed  milk  in  the  pan,  he  starts  the  motor. 
The  pump  immediately  fills  the  cylinder  and  the  hydrometer 
sffcqws  the  density  or  Beaume  reading. 

Drawing  off  the  Condensed  Milk. — As  soon  as  the  evapora- 
tion is  completed,  the  steam  is  shut  off  from  the  jacket  and  coils, 
the  water  valve  is  closed,  the  vacuum  pump  stopped  and  the 
vacuum  broken  by  opening  the  "blow-down"  valve.  The  man- 
hole cover  is  then  removed  and  the  vacuum  pump  started  again 
in  order  to  remove  pielpt  air  over  the  milk.  The  milk  is  drawn 
into  40-quart  cans  or  inter  tanks  or  cooling  vats.  The  condensed 
milk  should  be  drawn  from  the  pan  as  rapidly  as  possible  to 
prevent  its  superheating  while  in  the  pan.  In  some  factories  a 
wire  mesh  or  cloth  strainer  is  attached  to  the  outlet  of  the  pan, 
so  that  the  condensed  milk  is  strained  before  it  runs  into  the 
cans.  This  practice  is  unnecessary  and  objectionable,  as  it  tends 
to  retard  the  removal  of  the  milk  from  the  pan. 

COOLING 

The  sweetened  condensed  milk,  as  it  comes  from  the  vacuum 
pan,  has  a  temperature  of  about  115°  F.  to  130°  F.  If  it  were 
allowed  to  cool  naturally,  or  on  its  own  accord,  i.  e.,  if  no  effort 
were  made  to  cool  it  promptly,  it  would  superheat  and  this  would 
cause  it  to  become  thick  and  cheesy  in  a  short  time.  It  is,  there- 
fore, essential  that  it  be  cooled  at  once.  Formerly  this  was  done 
by  drawing  the-  milk  from  the  pan  into  40  quart  cans,  setting 
these  filled  cans  in  tanks  with  ice  water  and  stirring  the  con- 
densed milk  with  a  stick. 

This  was  a  very  crude  method,  it  involved  much  hard  work 


SWEETENED  CONDENSED  MILK — COOUNG  95 

and  time,  and  the  quality  of  the  product  was  poor.  It  was  soon 
found  that  the  imperfect  hand  stirring  caused  excessive  sugar 
crystallization,  which  made  the  milk  sandy.  The  sudden  chilling 
and  irregular  stirring  of  a  saturated  sugar  solution  like  sweet- 
ened condensed  milk  are  favorable  to  the  formation  of  sugar 
crystals.  Where  the  stirring  is  imperfect  and  irregular,  all  the 
milk  is  not  kept  in  sufficient  motion  to  insure  uniform  and  gradual 
cooling.  The  milk  next  to  the  side  of  the  cans  is  chilled  too 
abruptly,  favoring  the  formation  of  crystals.  Vigorous  stirring 
in  itself  is  conducive  of  sugar  crystallization. 

Later  the  hand  stirring  was  completely  superseded  by 
mechanical  stirring,  paddles  closely  scraping  the  sides  of  the  cans 
being  used.  Instead  of  setting  the  paddles  in  motion,  they  are 
stationary  and  the  cans:  revolve.  The  principle  is  similar  to  that 
of  the  vertical  ice  cream  freezer.  Heavy  iron  tanks,  with  a 
capacity  of  twelve  to  forty-eight  40-quart  cans,  are  used  for  this 
purpose.  The  bottoms  of  these  tanks  are  equipped  with  a  system 
of  cog  wheels,  set  in  motion  by  means  of  a  gear  at  one  end  of  the 
tank.  The  wheels  have  a  diameter  large  enough  to  carry  one 
can  each.  The  cans  are  set  on  these  wheels,  the  paddles  are 
inserted  and  fastened  to  cross-bars  and  the  power  started.  The 
cans  should  be  heavily  constructed  to  stand  rough  usage,  with- 
out suffering  indentations.  Cans  with  irregular,  depressed,  or 
bulged  sides  cause  the  paddles  to  do  poor  work,  i  Such  cans 
should  be  slipped  over  a  wooden  horn,  or  other  contrivance,  and 
the  indentations  hammered  out  with  a  mallet.  The  paddbfs  a?e 
held  stationary  by  cross-bars  and  are  forced  against  the  periphery 
of  the  cans  by  springs.  Attention  should  also  be  paid  to  the 
pivots  on  which  the  cog  wheels  rest.  If  they  are  warped,  the 
wheels  do  not  run  true,  so  that  it  is  not  possible  for  the  paddjes 
to  scrape  the  sides  of  the  cans  properly. 

The  sweetened  condensed  milk  should  be  cooled  gradually. 
Sudden  chilling  should  be  avoided.  This  is  best  accomplished 
by  warming  the  water  in  the  cooling  tank  to  about  90  degre.es  P., 
before  the  cans  are  set  in.  The  cans  are  then  allowed  to  revolve 
for  fifteen  to  twenty  minutes  before  any  cold  water  is  turned 
into  the  tank.  After  that,  cold  water  is  turned  in  slowly  until 
the  temperature  of  the  milk  has  fallen  to  about  70  degrees  F.  The 


96 


SWEETENED  CONDENSED  MILK — COOUNG 


entire  time  of  cooling  should  last  about 
two  hours.  The  cans  should  revolve 
slowly,  rapid  stirring  enhances  the 
precipitation  of  sugar  crystals.  In  order 
to  scrape  the  sides  of  the  cans  efficient- 
ly, when  the  cans  revolve  slowly, 
(about  five  revolutions  per  minute)  it 
is  advisable  to  use  two  paddles  in  each 
can,  scraping  the  cans  at  opposite  sides. 
When  the  milk  is  sufficiently  cooled 
the  cans  are  stopped,  the  paddles  lifted 
out,  spraped  and  removed,  and  the 
cans  taken  out  of  the  tank.  This  me- 
thod of  cooling  sweetened  condensed 
milk  is  still  in  vogue  in  the  majority  of 
condenseries.  It  is  obiviously  crude, 
suming. 


Fig.    30.     Vertical    coil    cooler 
Courtesy  of  Jensen  Creamery  Machinery  Co. 


Fig.    29.     Cooling   tank    for 

sweetened   condensed    milk 

Courtesy  Arthur  Harris  &  Co. 


laborious   and   time-con- 

In  some  factories  the 
condensed  milk  is  trans- 
ferred from  the  pan  di- 
rect into  large  tanks  and 
is  subsequently  cooled 
by  pumping  it  with 
a  high  pressure  pump 
through  a  series  of  coils 
submerged  in  cold  wa- 
ter. This  method  is 
labor  and  time-saving 
and  the  objectionable 
features  of  agitation  are 
avoided.  On  the  other 
hand,  there  is  danger 
of  too  rapid  chilling, 
which  tends  toward  ex- 
cessive sugar  crystalli- 
zation and  the  produc- 
tion of  rough,  sandv 
and  settled  milk. 


CONDENSED  MILK — FIWJNG  97 

Within  recent  years  the  use  of  circular  tanks  with  jacket  and 
vertically  suspended,  revolving  coil,  has  been  adopted  in  numerous 
factories  with  most  satisfactory  results,  and  this  method  of  cooling 
this  viscous  product  promises  to  greatly  assist  to  solve  the  cooling 
problem.  Rectangular  vats  with  horizontal  coils,  which  also  have 
been  tried  for  this  purpose,  however,  are  less  desirable,  as  they 
tend  to  cause  the  condensed  milk  to  foam  excessively.  This  foam- 
ing is  caused  by  the  fact  that  the  horizontal  coil  revolves  into  the 
milk,  beating  air  into  it.  In  the  case  of  the  circulator  tank,  the 
vertical  suspended  coil  when  revolving  moves  upward,  out  of 
the  milk,  thus  avoiding  incorporation  of  air  and  excessive  foam- 
ing. The  circular  vat  with  the  suspended  vertical  coil  has  the 
further  advantage  that  the  condensed  milk  does  not  come  in 
contact  with  bearings  and  glands,  these  parts  being  entirely  de- 
tached from  the  vat.  For  prevention  of  gritty  and  settled  milk, 
see  also  Chapter  XXIII  on  "Condensed  Milk  Defects,"  page  191. 

CHAPTER  VII. 
FILLING 

The  sweetened  condensed  milk  is  put  on  the  market  in 
barrels  and  in  hermetically  sealed  tin  cans. 

In  Barrels. — Barrels,  similar  to  glucose  barrels,  are  generally 
used.  They  hold  from  three  hundred  to  seven  hundred  pounds 
of  condensed  milk.  New  barrels  should  be  used  for  this  purpose. 
Barrels  paraffined  on  the  inside  are  most  satisfactory,  as  they  are 
more  apt  to  be  free  from  mold  spores.  Old  glucose  barrels  are 
dangerous  to  use,  as  they  often  contain  decaying  remnants  of 
glucose,  which  cause  the  condensed  milk  to  ferment.  The  new 
barrels  are  steamed  out  and  drained  thoroughly.  The  filling  is 
facilitated  by  the  use  of  a  large  galvanized  iron  funnel  with  a 
discharge  one  and  one-half  inches  in  diameter,  or  an  ordinary 
milk  pail  with  a  nipple  one  and  one-half  inches  in  diameter  in 
the  bottom  of  the  pail.  When  filled,  a  double  layer  of  cheese 
cloth  is  placed  over  the  bunghole,  and  the  bung  is  driven  in  level 
with  the  staves.  The  barrel  goods  are  sold  to  bakeries  and  candy 
factories. 

In  Cans. — The  canned  goods  are  intended  for  the  retail 
market.  The  cans  used  hold  from  eight  ounces  to  one  gallon  of 
condensed  milk.  Most  makes  of  tin  cans  for  sweetened  condensed 


98 


SWEETENED  CONDENSED  MILK — 


milk  have  a  small  opening-,  three-eights  to  three-fourths  inch  in 
diameter  through  which  they  are  rilled.  The  cans  known  and  sold 
under  the  trade  name  "sanitary  can"  are  filled  before  the  top  is 
crimped  on.  Sweetened  condensed  milk  is  of  a  semi-fluid,  viscous 
and  sticky  consistency.  The  successful  and  rapid  filling  of  the  cans 
without  spilling  the  milk  over  the  top  of  the  can  is,  therefore, 


Fig.  31.     The  solder  seal 


Fig.    32.     The    Sanitary    can 


Fig.  33.     The  Gebee  seal 


Fig.  34.     The  McDonald  seal 


somewhat  difficult.  If  done  by  hand  the  work  is  very  slow.  For 
this  reason  many  ingenious  machines  have  been  devised  which 
are  more  or  less  efficient  in  "cutting  off"  the  milk  without  "slob- 
bering." The  filling  machines  now  in  use  vary  from  the  primitive 
hand  filler,  in  which  the  condensed  milk  is  "ground  out"  by  the 
turning  of  a  crank  by  hand,  to  the  most  perfect  forms  of  automatic 
filling  machines.  In  these  filling  machines,  all  parts  coming  in 
contact  with  the  condensed  milk  are  constructed  of  brass.  They 
usually  are  equipped  with  a  reservoir,  receiving  tank,  or  hopper, 
which  has  an  automatic  feed,  usually  a  floating  device  attached  to 
a  valve,  which  regulates  the  inflow  according  to  the  discharge. 


SWEETENED  CONDENSED  MILK — SEALING  99 

The  discharge  is  adjustable  to  fill  any  size  can  with  a  remarkable 
degree  of  accuracy  except  gallons  which  are  usually  filled  by 
hand.  Machines  of  this  type  will  fill  from  twenty-five  thousand 
to  thirty  thousand  cans  per  day  (ten  hours.) 

These  machines  are  of  complex  construction  and  must  re- 
ceive proper  care.  It  is  best  to  clean  them  thoroughly  after  each 
day's  work.  But,  since  their  inlet  and  discharge  are  closed  her- 
metically, the  complete  washing  may  be  done  once  per  week  only, 
without  seriously  disturbing  their  efficiency  or  impairing  the 
product.  For  thorough  cleaning,  the  filler  should  be  dissected, 
removing  all  detachable  parts,  such  as  valves,  pistons,  tubes,  etc. 
When  freed  from  all  remnants  of  condensed  milk,  the  parts 
should  be  scalded,  dried  and  replaced  in  the  machine.  In  order 
to  guard  against  all  possible  contamination  by  remnants  of  wash 
water,  it  is  advisable  to  reject  the  first  few  cans  of  milk  of  the 
next  filling.  When  not  in  use,  the  filling  machine  should  be 
covered  with  clean  cloth,  or  oil  cloth,  to  protect  it  from  dust  and 
flies,  etc. 

As  soon  as  the  cans  are  filled,  they  should  be  "capped."  If 
allowed  to  stand  open,  dust,  dirt  and  flies,  or  other  insects  are 
prone  to  reach  their  interior,  and  the  prolonged  exposure  of  the 
condensed  milk  to  the  air  and  light  causes  the  surface  to  crust 
over  and  to  develop  a  tallowy  flavor. 

SEALING 

Kinds  of  Seals. — The  seal  must  be  air-tight  and  firm  enough 
to  prevent  its  breaking  during  the  rough  treatment  to  which  the 
cans  are  exposed  in  transportation.  There  are  several  methods 
of  sealing  the  cans,  depending  largely  on  the  construction  of  the 
can.  Most  of  the  cans  used  are  sealed  with  solder.  There  is  a 
groove  around  the  opening,  the  periphery  of  the  cap  fits  into  this 
groove  and  the  latter  is  filled  with  solder.  In  the  case  of  cans 
which  are  sealed  without  solder,  the  cap  or  the  entire  end  of  the 
can  is  criped  onto  the  can  so  as  to  make  a  hermetical  seal.  The 
McDonald  seal  with  the  friction  cap,  the  Gebee  seal  with  the  burr 
cap,  and  the  Sanitary  can  seal  with  the  top  of  the  can  crimped  on 
after  filling,  are  the  chief  types  of  solderless  seals.  In  the  case  of 
the  McDonald  seal,  a  tig'htly  fitting  cap  with  a  wide  flange  is 
pressed  into  the  opening.  The  "capped"  can  passes  under  a  series 
of  steel  rollers  pressing  the  flange  firmly  against  the  top  of  the 


100 


CONDSNSSD  MILK — 


can.  This  seal  is  very  simple,  but  is  not  very  strong  and  not 
hermetically  tight.  In  the  case  of  the  Gebee  seal,  a  rim  projects 
around  the  opening  of  the  can.  After  the  cap  is  inserted,  it  is 
crimped  over  this  rim  by  means  of  a  series  of  revolving  dies.  This 
seal  is  reasonably  strong  but  not  hermetically  tight.  The  Sanitary 
can  is  entirely  open  at  one  end  when  filled.  The  cover  or  end  is 
crimped  around  the  periphery  of  the  body  of  the  can  by  means 
of  revolving  dies.  This  seal  is  reasonably  strong  and  usually 
hermetically  tight. 

The  chief  advantages  of  the  seals  without  solder  lie  in  the 
saving  of  labor,  and  the  reduction  of  the  cost  due  to  the  omission 
of  solder.  The  principal  reason  for  which  some  of  them  are  not 
used  more  generally  by  milk  condensing  companies,  lies  in  the 
fact  that  these  solderless  seals  are  all  patented.  In  most  cases 
the  inventors  or  patent  holders  are  condensed  milk  manu- 
facturers. They  refuse  to  sell  their  pa- 
tents at  a  reasonable  price  to  other 
condenseries  and  they  charge  exor- 
bitant royalties  for  the  use  of  their 
patents  by  their  competitors.  With  the 
possible  exception  of  the  "  Sanitary 
can,"  solderless  seals  are  not  as  re- 
liable as  solder  seals. 


Fig.  36.     Soldering  stove 
Courtesy  of  Arthur  Harris  &  Co. 

Soldering  Devices  and  Machinery. 

The  sealing  of  all  solderless  seals  is 
done  by  specially  constructed  sealing 
machines. 

For  seals  with  solder  there  are  sev- 
eral machines  on  the  market  but  much 


. 


Fig.  35.     A  convenient  de- 
vice for  soldering  by  hand 


SWEETENED  CONDENSED  MILK — SEALING  101 

of  this  work  is  as  yet  done  by  hand.  For  this,  different  types  of 
soldering-  coppers  are  in  use  and  the  copper  tips  are  heated  in 
soldering  stoves  or  pots.  Some  soldering1  coppers  have  hollow 
circular  tips  with  a  diameter  equal  to  that  of  the  cap  used. 
The  hollow  tip  is  telescoped  by  a  rod  which  holds  the  cap  in 
place  and  the  periphery  of  the  tip  fits  into  the  groove  of  the 
opening  of  the  can,  where  it  melts  the  solder.  A  rapid,  neat  and 
leakless  seal  can  be  made  with  this  instrument. 

Ordinary  soldering  coppers  with  a  blunt  point,  such  as  are  in 
general  use  by  the  tin  smith,  are  not  very  satisfactory.  Unless 
they  are  drawn  out  and  filed  down  into  a  fine  point,  their  use  is 
not  conducive  of  neat  work,  progress  is  comparatively  slow  and 
leakers  are  often  numerous.  When  gas  is  available  the  automatic 
soldering  copper  may  be  used  to  advantage.  In  this  tool  the 
copper  tip,  which  is  long  and  slender  is  automatically  heated  by 
a  current  of  gas  passing  through  the  handle  and  burning  at  the 
copper  tip.  The  handle  of  the  device  is  connected  with  the  gas 
and  air  pipes  by  means  of  flexible  rubber  tubing.  No  time  is 
lost  waiting  for  the  coppers  to  heat  and  the  flame  can  be  so 
regulated  that  the  temperature  of  the  copper  tip  is  right  and 
uniform.  This  is  important,  because  perfect  work  is  impossible 
unless  the  coppers  have  the  proper  temperature. 

Machine-soldering  is  now  rapidly  replacing  hand-solder- 
ing. The  principle  of  the  older  types  of  soldering  machines  con- 
sisted of  revolving  discs  on  which  the  tin  cans  were  placed.  The 
cap  was  held  in  place  by  a  vertical  rod  pressing  on  it.  The  solder 
was  applied  by  hand,  the  hot  soldering  copper  was  held  over  the 
groove  in  the  can  while  the  cans  revolved.  This  method  had  no 
particular  advantage  over  the  hand  soldering.  There  was  little, 
if  any,  saving  of  time  and  the  quality  of  the  work  was  not  much, 
if  any,  better. 

There  are  now  on  the  market  newer  types  of  soldering  ma- 
chines, most  ingeniously  constructed  and  their  operation  in  fac- 
tories with  large  outputs  economize  labor  and  time.  When 
operated  by  a  skillful  mechanic  they  do  very  creditable  work. 

Solder. — The  solder  used  for  sealing  should  be  of  standard 
composition.  In  this  country,  canning  establishments  are  prone 
to  use  a  very  poor  quality  of  solder.  It  contains  from  45  to  55 
per  cent  lead.  Lead  is  a  poisonous  metal ;  its  use  in  the  canning 


102  SWEETENED  CONDENSED  MILK — SEAUNG 

industry  should,  therefore,  be  regulated  by  law.  In  Germany, 
the  law  requires  that  solder  used  in  tin  cans  for  food  products 
must  not  contain  over  10  per  cent  of  lead. 

Where  the  sealing  is  done  by  hand  the  solder  is  most  con- 
veniently used  in  the  form  of  thin  bars  or  wire.  The  wire  is 
usually  bought  already  cut  up  in  segments,  each  segment  furnish- 
ing solder  enough  to  seal  one  can.  In  the  newer  types  of  soldering 
machines  the  solder  wire  is  automatically  fed  from  spools.  The 
smaller  the  opening  of  the  can,  the  less  solder  is  necessary  to 
complete  the  seal.  An  opening  smaller  than  three-eights  of  an 
inch  in  diameter,  however,  cannot  conveniently  be  used,  owing 
to  the  difficulty  of  filling  the  can  with  this  viscous  product.  The 
essential  points  of  satisfactory  sealing  are:  no  "leakers"  neat 
work,  rapid  work,  small  amount  of  solder.  Aside  from  the  size 
of  the  opening  of  the  can,  the  amount  of  solder  used  depends 
on  the  experience  of  the  sealer.  Beginners  usually  make  an  un- 
even seal,  waste  much  solder,  and  have  many  "leakers."  This 
is  largely  due  to  their  ignorance  of  the  proper  soldering  tempera- 
ture of  the  coppers.  An  experienced  sealer  will  use  from  two 
to  three  pounds  of  solder  per  thousand  tin  cans  with  moderate- 
sized  openings.  He  will  seal  from  fifteen  hundred  to  twenty-five 
hundred  cans  per  day. 

Soldering  Flux. — The  use  of  solder  requires  the  application 
of  soldering  flux,  to  prepare  the  surface  of  the  tin  for  the  solder. 
The  flux  always  precedes  the  solder.  When  the  hot  solder  is 
applied,  some  of  the  flux  is  bound  to  sweat  through,  between  cap 
and  can,  gaining  access  to  the  interior  of  the  can.  The  common 
practice  of  using  zinc  chloride  or  other  similar  acid  fluxes,  which 
are  highly  poisonous,  therefore,  cannot  be  too  strongly  con- 
demned. Their  presence  in  the  can  may  jeopardize  the  health 
and  life  of  the  consumer,  as  well  as  the  marketable  properties  of 
the  product.  There  are  other  fluxes  which  are  absolutely  harm- 
less, and  which,  if  properly  used,  give  satisfactory  results.  Dry, 
powdered  resin,  or  resin  dissolved  in  alcohol  or  gasoline,  are  of 
this  class.  Ammonium  chloride,  while  used  in  most  tin  shops, 
is  not  as  well  suited  for  this  purpose. 

Gas  Supply. — A  plentiful  and  steady  supply  of  gas  is  very 
essential.  Where  natural  gas  or  gas  from  a  municipal  corpora- 


SWEETENED  CONDENSED  MILK — SEAUNG  103 

tion  is  not  available,  the  factory  must  rely  on  its  own  generator. 
For  the  needs  of  the  condensery  a  gasoline  gas  plant  seems 
suitable.  Gasoline  gas  is  produced  by  forcing  atmospheric  air 
over  or  through  a  body  of  gasoline.  The  mixture  of  air  and 
gasoline  vapors  forms  the  gasoline  gas.  The  gas  generators  in 
use  consist  chiefly  of  carburetor,  air  pump  or  blower,  and  regu- 
lator. The  carburetor  usually  has  a  series  of  cells,  connected 
with  one  another  by  means  of  a  system  of  syphon  tubes.  The 
interior  of  each  cell  is  partitioned  off  with  heavy  cotton  wicking. 
This  wicking  absorbs  the  gasoline  by  capillary  attraction.  The 
air,  passing  through  the  fine  meshes  of  wicking,  comes  in  contact 
with  a  large  surface  of  gasoline. 

The  following  are  some  of  the  essential  points  to  be  observed 
in  the  installation  and  operation  of  gas  generators  of  this  type: 
Sink  the  carburetor  low  enough  (three  to  five  feet  below  the 
surface  of  the  ground  if  necessary)  to  permit  the  gas  pipe  to  slant 
from  the  factory  to  the  carburetor.  If  the  gas  pipe  is  horizontal, 
or  inclined  toward  the  factory,  condensation  water  may  collect 
in  the  pipe,  obstructing  the  free  passage  of  gas.  This  causes  the 
gas  either  not  to  be  available  at  all.  or  to  reach  the  stoves  in 
irregular  gusts,  which  is  equally  unsatisfactory.  Where  the  gas 
pipe  slants  toward  the  carburetor,  the  condensation  water  flows 
back  into  the  carburetor,  causing  no  obstruction.  Use  gasoline 
of  the  best  quality  only.  Cheap  grades  form  a  residue  and  clog 
the  generator.  The  gasoline  is  best  bought  in  iron  barrels ;  this 
prevents  unnecessary  loss  by  evaporation,  which  occurs  in  wooden 
barrels,  especially  in  summer.  The  cells  should  not  be  filled  more 
than  two-thirds  full ;  too  much  gasoline  reduces  the  gas-genera- 
ting capacity  of  the  carburetor.  If,  during  extremely  cold 
weather,  the  carburetor  refuses  to  generate  gas,  the  injection  of 
a  pint  of  wood  alcohol  through  the  blow  pipe  into  the  cells, 
usually  remedies  the  trouble.  The  gas  plant  and  gasoline  storage 
should  be  located  in  a  separate  building  and  at  a  reasonable 
distance  from  the  main  building,  in  order  to  minimize  danger 
from  fire. 


PART  III 

MANUFACTURE  OF  UNSWEETNED  CON- 
DENSED  MILK 

EVAPORATED  MILK 

CHAPTER  VIII. 
DEFINITION 

There  are  three  kinds  of  unsweetened  condensed  milk  on 
the  market,  namely,  evaporated  milk,  formerly  called  eavapor- 
ated  cream,  plain  condensed  bulk  milk  and  concentrated  milk. 

Evaporated  milk  is  cow's  milk  condensed  in  vacuo  at  the 
ratio  of  about  two  to  two  and  one-half  parts  of  fresh  milk  to  one 
part  of  condensed  milk.  It  is  of  the  consistency  of  thin  cream 
and  reaches  the  market  in  hermetically  sealed  cans  varying  in 
size  from  eight  ounces  to  one  gallon.  Evaporated  milk  is  pre- 
served by  sterilization  in  steam  under  pressure.  When  properly 
made,  it  will  keep  indefinitely,  but  is  best  when  fresh. 

QUALITY    OF    FRESH    MILK 

In  the  manufacture  of  evaporated  milk  the  physiological 
normality  and  the  chemical  purity  and  sweetness  of  the  fresh- 
milk  are  factors  even  more  important  than  in  the  case  of  sweet- 
ened condensed  milk.  A  uniformly  satisfactory  and  marketable 
product  cannot  be  manufactured,  unless  the  milk  is  normal  and 
pure  in  every  respect.  The  reason  for  this  largely  lies  in  the 
fact,  that  defects  the  fresh  milk  may  have,  are  greatly  magnified 
and  intensified  by  the  high  sterilizing  temperature  to  which  the 
evaporated  milk  is  subjected.  While,  from  the  biological  point 
of  view,  contaminations  of  this  milk  are  largely  rendered  harm- 
less by  sterilization,  defective  fresh  milk  cannot  be  made  into 
a  marketable  product,  because  such  milk  usually  does  not  survive 
the  process. 

It  should  be  understood  that  any  condition  or  factor  that, 
in  the  slightest  degree,  increases  the  tendency  or  ability  of  the 


EVAPORATED  MILK — HEATING  105 

casein  to  curdle,  tends  toward  the  formation  of  a  hard,  unshak- 
able coagulum  during1  sterilization,  and  makes  the  manufacture 
of  a  marketable  product  difficult.  Abnormal  milk  of  this  type 
may  come  from  cows  approaching  parturition,  or  too  soon  after 
calving,  or  milk  from  cows  suffering  from  disease,  generalized 
or  local,  or  from  cows  in  poor  and  abnormal  physical  condition, 
which  may  be  brought  about  by  poor  care,  over-feeding,  feeding 
the  wrong  kinds  of  feed,  or  feed  in  poor  condition,  exposure  to 
abnormally  hot  weather  and  flies,  or  any  other  condition  which 
disturbs  the  physiological  functions  of  the  animal  and  thereby 
affects  the  physical,  chemical,  and  physiological  properties  of 
the  milk;  or  it  may  be  due  to  improper  care  of  the  milk,  causing 
it  to  be  excessively  contaminated  with  germ  life,  or  to  be  re- 
latively high  in  acid.  All  such  milk  renders  the  quality  of  the 
finished  product  uncertain  and  may  result  in  heavy  loss. 

In  view  of  these  facts  it  is  obvious  that  the  greatest  care 
should  be  exercised  on  the  receiving  platform,  inspecting  every 
can  of  milk,  using  the  most  reliable  means,  as  recommended  in 
Chapter  III  on  " Control  of  Quality,"  p.  43,  to  detect  suspicious 
milk,  and  rejecting  all  milk  that  fails  to  reach  the  sanitary 
standard  adopted  by  the  factory. 

• 
HEATING  THE  MILK 

The  equipment  for  heating  the  milk  should  be  such  as  to 
enable  the  factory  to  heat  the  milk  with  the  least  possible  delay, 
so  as  to  avoid  the  development  of  acid  or  to  make  possible  the 
prompt  cooling  of  the  milk  upon  its  arrival  to  a  temperature  at 
which  bacterial  development  is  checked.  In  the  manufacture  of 
evaporated  milk,  the  batches  of  condensed  milk  in  the  vacuum 
pan  must  be  relatively  small.  This  milk  foams  more  in  the  pan 
than  the  heavier  sweetened  condensed  milk.  This  factor 
reduces  therefore,  the  capacity  of  the  pan.  If  the  milk  is  not 
cooled  upon  arrival,  but  is  transferred  immediately  to  the  hot 
wells,  it  is  advisable  to  use  numerous  small  wells,  rather  than 
but  one  or  a  few  large  ones.  These  small  wells  fill  rapidly  and 
the  milk  can  be  heated  without  delay.  This  system  makes  it 
possible  to  render  the  bacteria  inactive  and  harmless  practically 


106  EVAPORATED  MILK — CONDENSING 

as    soon    as   the    milk   arrives,   minimizing-   the   danger   of   acid 
formation.1 

Steam  may  be  saved  if  the  milk  is  forewarmed  by  running 
it  through  coils  inclosed  in  a  chamber  of  exhaust  steam,  but  the 
coils  increase  the  labor  and  difficulty  of  cleaning.  It  is  best  to 
heat  the  milk  to  as  near  the  boiling  point  as  possible  and  hold  it 
there  for  five  to  ten  minutes,  provided  that  the  capacity  of  the 
factory  warrants  this  delay.  In  this  heating  the  casein  of  the 
milk  is  somewhat  changed.  There  occurs  partial,  though  invis- 
ible, precipitation,  and  the  higher  the  temperature  to  which  the 
milk  is  heated,  the  more  pronounced  is  this  change.  This  change 
is  desirable,  because  the  casein  thereby  surrenders,  to  a  limited 
extent,  its  power  and  tendency  to  form  a  firm  curd  in  the  steril- 
izer. 

CONDENSING 

The  same  apparatus,  the  vacuum  pan  and  pump,  is  used 
for  condensing  the  milk,  and  the  process  of  condensing  is  prin- 
cipally the  same,  as  in  the  case  of  sweetened  condensed  milk. 
The  fresh  milk  is  condensed  at  the  ratio  of  two  to  two  and  one- 
half  parts  of  fresh  milk  to  one  part  of  condensed  milk.  In  some 
factories  it  is  customary  to  superheat  the  milk  in  the  pan  before 
it  is  drawn  off,  i.  e.,  the  steam  to  the  jacket  and  coils  is  shut  off, 
trte  water  valve  is  closed,  the  vacuum  pump  is  stopped  and 
"live"  steam  is  passed  into  the  condensed  milk.  When  the 
vacuum  has  dropped  to  about  six  to  eight  inches,  and  the  tem- 
perature has  risen  to  180  to  200°  F.  the  superheating  is  stopped, 
the  steam  is  turned  off,  the  vacuum  pump  is  started  again,  and 
the  condensing  is  completed.  The  superheating  is  frequently 
also  done  after  the  evaporated  milk  has  been  drawn  from  the 
pan.  In  this  case,  the  process  of  evaporation  is  usually  carried 
slightly  beyond  the  desired  density  of  the  finished  product,  the 
evaporated  milk  is  drawn  from  the  pan  into  an  open  vat  or 
kettle  where  steam  is  turned  direct  into  the  milk  until  the  super- 
heating is  completed,  which  is  indicated  by  its  greater  consist- 
ency and  the  slightly  flaky  condition  of  the  curd.  Then  water  is 
added  to  the  superheated  evaporated  milk  to  bring  the  product 
back  to  the  desired  density. 

The  chief  purpose  of  superheating  is  to  partly  precipitate 

1  See  also  Cooling  Milk,  p.  52,  and  Standardization,  p.  253. 


EVAPORATED   MILK — STRIKING  107 

the  curd.  This  minimizes  the  danger  of  the  formation  of  too 
hard  a  curd  in  subsequent  sterilization.  It  also  lends  the  body 
of  the  milk  the  appearance  of  greater  consistency,  gives  it  a 
more  viscous  character  and  assists  in  the  prevention  of  sub- 
sequent fat  separation.  The  superheating  of  evaporated  milk  is 
not  essential  for  the  production  of  quality  and  marketable  prop- 
erties, but  it  is  looked  upon  by  many  manufacturers  as  a  safe- 
guard against  such  defects  as  curdiness  and  fat  separation.  It 
is  not  improbable  that  its  advantages  are  much  overestimated, 
and  in  most  factories  the  superheating  process  is  entirely  omitted. 

The  condensing  of  milk  for  the  purpose  of  manufacturing 
evaporated  milk  may  be  done  also  in  the  absence  of  the  vacuum 
pan,  by  the  use  of  the  "Continuous  Concentrator,"  the  construc- 
tion and  operation  of  which  are  described  on  pages  133  to  141. 

STRIKING 

The  striking,  or  sampling  and  testing  for  density,  of  evapor- 
ated milk,  is  more  easily  accomplished  than  that  of  the  sweetened 
condensed  milk.  When  this  product  has  nearly  reached  the 
proper  density,  it  is  not  viscous  and  syrupy,  containing  no  cane 
sugar.  It  resembles  in  consistency  rich  milk  or  thin  cream  and 
has  a  specific  gravity  of  1.05  to  1.075  at  15.5  degrees  C.  or  60 
degrees  F. 

Samples  are  drawn  from  the  vacuum  pan  as  described  under 
sweetened  condensed  milk  and  the  density  can  be  readily  deter- 
mined by  means  of  a  hydrometer.  Beaume  hydrometers,  register- 
ing from  5  to  15  degrees  B.,  are  generally  used.  As  it  is  im- 
portant that  the  determinations  be  accurate,  the  hydrometer 
should  be  sensitive  and  its  scale  should  be  subdivided  into  tenth 
degrees.  The  batch  should  be  "struck"  at  a  uniform  temper- 
ature, say  120  degrees  F.,  so  as  to  avoid  misleading  readings  of 
the  hydrometer.  A  difference  of  a  few  tenths  degrees  Beaume 
affects  the  behavior  of  the  evaporated  milk  in  the  sterilizer  very 
appreciably.  If  the  density  is  too  great  the  product  may  badly 
curdle  during  sterilization.  If  the  density  is  too  low  the  evapor- 
ated milk  may  be  below  the  legal  standard.  It  is  advisable  for 
the  operator  to  use  a  pail  of  water  of  the  proper  temperature, 
when  he  strikes  the  batch,  so  that  he  can  adjust  the  temperature 
of  the  milk  in  the  hydrometer  jar  readily  and  quickly,  and  need 


108  EVAPORATED  MII.K — STRIKING 

not  depend  entirely  on  the  temperature  of  the  milk  in  the  pan 
which  may  change  several  degrees  while  he  is  engaged  in  the 
operation  of  striking. 

While  the  Beaume  hydrometers  should  be  used  at  the  tem- 
perature for  which  they  are  graduated,  which  is  60  degrees  F., 
they  answer  all  practical  purposes  at  any  other  temperature: 
at  120  degrees  F.  for  instance.  The  chief  essential  is  to  take  the 
reading  at  some  uniform  and  definite  temperature  and  read  the 
Beaume  at  that  same  temperature  in  the  case  of  every  batch.  In 
that  way  the  results  are  comparable.  The  operator  soon  learns 
that  at  a  given  temperature  the  evaporated  milk  of  proper 
density  shows  a  certain  Beaume  reading.  When  the  reading  is 
higher  or  lower,  the  milk  has  either  been  condensed  too  much  or 
not  enough.  The  use  of  the  automatic  "striker"  described  under 
"Striking  Sweetened  Condensed  Milk,"  practically  solves  the 
control  of  the  temperature  of  the  sample  taken. 

The  same  formula,  however,  cannot  be  used  under  all  condi- 
tions. No  rule-of-thumb  method  of  determining  the  density  can 
therefore  be  established.  Aside  from  the  degree  of  condensation, 
the  specific  gravity  of  the  milk  varies  with  locality,  season  of 
year,  quality  of  milk,  etc.  This  means  that  what  is  the  proper 
Beaume  reading  in  one  locality,  or  at  one  season  in  the  same 
locality,  may  be  entirely  wrong  in  another  locality  or  at  other 
seasons  in  the  same  locality.  If  uniformity  in  the  density  and 
behavior  of  the  batches  of  evaporated  milk  is  to  be  secured 
throughout  the  year,  the  operator  must  watch  the  behavior  of 
his  milk  from  day  to  day  and  from  season  to  season  and  he 
must  modify  the  Beaume  reading  in  accordance  with  the  changing 
conditions.  This  is  one  of  the  all  important  stages  of  manufac- 
ture, where  relentless  and  careful  study  and  watchfulness  are 
indispensable. 

In  order  to  make  absolutely  sure  that  the  density  of  the  evap- 
orated milk  is  right,  it  is  advisable  to  get  it  just  as  near  right 
as  possible  in  the  pan  and  then  draw  the  milk  from  the  pan 
into  a  standardizing  vat,  large  enough  to  accomodate  the 
entire  batch  or  several  batches.  The  operator  then  tests  the  milk 
again  and  this  second  estimation  he  can  perform  more  carefully, 
because  he  is  then  relieved  of  the  responsibility  of  attending  to  the 


EVAPORATED   MILK — STRIKING  109 

operation  of  the  vacuum  pan.  If  the  evaporated 
milk  happens  to  be  a  trifle  too  heavy  he  can  dilute 
it  with  distilled  water  until  the  Beaume  reading 
is  just  right.  See  also  " Standardization,"  Chapter 
XXXIX,  page  253. 

Correction  of  Beaume  Reading  at  Temperatures 
Other  than  60  Degrees  F. — At  a  temperature  of  120 
degrees  F.  the  Beaume  reading  of  the  finished  batch 
of  standard  evaporated  milk  may  vary  between 
about  6  and  8  degrees  B.,  according  to  season  of 
year  and  locality.  At  60  degrees  F.  the  Beaume 
reading  is  approximately  1.83  degrees  B.  higher. 

If  it  is  desired  to  record  the  Beaume  reading 
at  the  correct  temperature,  i.  e.,  60  degrees  F.,  and 
it  is  not  convenient  to  cool  the  evaporated  milk  to 
that  temperature,  the  reading  at  any  temperature 
may  be  corrected  as  follows :  when  the  temper- 
ature at  which  the  Beaume  reading  is  taken  is  above 
60  degrees  F.,  multiply  the  difference  between  the 
temperature  of  the  observed  reading  and  60  by  the 
factor  .0313  and  add  the  product  to  the  observed 
reading. 

Example:   Beaume  at  120  degrees  F.  is  6.8;  what 
is  the  reading  at  60  degrees  F.  ? 
Answer:    6.8  +  (60  X  .0313)  =  8.68  degrees  B. 

The  corrected  Beaume  reading  is  8.68  degrees  B. 
When  the  temperature  at  which  the  reading  is 
made  is  below  60  degrees  F.,  multiply  the  differ- 
ence between  the  temperature  of  -the  observed 
reading  and  60  by  the  factor  .0313  and  subtract 
the  product  from  the  observed  reading. 

Calculation  of  Specific  Gravity  from  Beaume 
Reading. — In  order  to  record  the  density  of  the  pig.  37. 

.        ...     .  -  .,,  ,    Beaume  hydro- 

evaporated  milk  in  terms  of  specific  gravity,  instead       meter  for 

of  Beaume  degrees    the  following  formula  may  be       'vam!!k  6 

Courtesy   of 

Used  :  C.  J.  Tagliabue 

Mfg.  Co. 


110  EVAPORATED  MII.K — HOMOGENIZING 

145  5 
Specific  gravity  =     1455^™     >  B  =  Beaume  reading  at  60 

degrees  F. 

Example:    Beaume  reading  at  60  degrees  F.  is  8  degrees  B. 
What  is  the  specific  gravity? 

145  5 
Specific  gravity  =  — —  =  1.0582 


CHAPTER  IX. 
HOMOGENIZING 

Purpose. — The  introduction  of  the  homogenizer  in  milk  con- 
densing factories  is  a  comparatively  recent  innovation.  The  ob- 
ject of  its  use  is  to  avoid  the  separation  of  the  butter  fat  in  the 
evaporated  milk  after  manufacture. 

The  butter  fat  is  present  in  milk  in  the  form  of  minute 
globules.  These  fat  globules  are  lighter  than  the  rest  of  the 
ingredients  of  the  milk.  They,  therefore,  show  a  strong  tendency 
to  rise  to  the  surface  and  to  form  a  layer  of  thick  cream  in  the 
cans.  When  these  cans  are  subsequently  subjected  to  agitation, 
as  is  the  case  in  transportation,  this  cream  churns,  forming  lumps 
of  butter.  This  tendency  of  evaporated  milk  to  separate  in  stor- 
age and  churn  in  transportation  is  especially  noticeable  with 
milk  rich  in  fat  und  in  Avhich  the  large  fat  globules  predominate. 
In  Jersey  and  Guernsey  localities,  it  is  more  difficult,  therefore, 
to  manufacture  evaporated  milk  that  does  not  separate,  than  in 
Holstein  and  Ayrshire  localities.  While  separated  and  churned 
evaporated  milk  is  perfectly  sound  and  in  every  way  as  valuable 
as  a  food,  as  it  would  be  without  this  separation,  it  does  not  sell 
in  this  condition.  It  is  rejected  on  the  market. 

This  tendency  toward  fat  separation  can  be  minimized  and 
frequently  entirely  prevented  by  increasing  the  viscosity  of  the 
evaporated  milk.  This  can  be  accomplished  by  superheating  the 
milk  in  the  pan  or  after  it  leaves  the  pan,  and  by  prolonging 
the  sterilizing  process,  raising  the  heat  very  slowly  or  stopping 
the  reel  of  the  sterilizer  at  certain  stages  of  the  process.  How- 


EVAPORATED  MILK — HOMOGENIZING  111 

ever,  there  are  conditions  when  even  these  precautions  do  not 
permanently  avoid  separation  of  the  fat.  In  such  cases,  the 
proper  use  of  the  homogenizer  furnishes  a  reliable  means  to 
guard  against  this  difficulty. 

Principle  of  the  Homogenizer. — The  principle  of  the  homo- 
genizer  is  to  force  the  milk  under  high  pressure  through  exceed- 
ingly small,  microscopic  openings.  By  so  doing  the  fat  globules 
are  broken  up  so  finely  that  they  fail  to  respond  to  the  gravity 
force,  they  cannot  rise  to  the  surface  and  therefore  remain  in 
homogeneous  emulsion.  The  value  of  the  homogenizer  lies  in 
removing  the  fundamental  cause  of  this  separation.  It  reduces 
the  fat  globules  to  such  small  size  that  their  buoyancy,  or  grav- 
ity force,  is  not  great  enough  to  overcome  the  resistance  of  the 
surrounding  liquid. 

The  tendency  of  fat  globules  to  separate  out  in  homogenized 
evaporated  milk  is  further  reduced  by  the  fact  that  the  homogen- 
izer also  alters  the  physical  condition  of  the  casein,  making  it 
more  viscous  and  thereby  increasing  the  resistance  which  the 
fat  globules  must  overcome  in  their  upward  'passage. 

Kinds  of  Homogenizers. — There  are  at  this  time  two  makes 
of  homogenizers  in  use  in  this  country,  namely,  the  "Gaulin" 
and  the  " Progress"  homogenizer. 

In  the  Gaulin 
'homogenizer,  the 
milk  is  forced,  by 
means  of  single- 
acting  pumps,  a- 
gainst  an  agate 
valve  which  pres- 
ses against  a 
ground  valve  seat. 
The  milk  has  to 
pass  between  the 

I  ^^     B^  ground  surfaces  of 

this  v  a  1  v  e  and 
valve  seat.  This 
causes  the  fat 

Fig.   38.     The   Progress   homogenizer  HobuleS    to   be   di- 

Courtesy  of  Davis-Watkins  Dairymen's  Supply  Company    5 


112 


EVAPORATED  MI^K — HOMOGENIZING 


vided  very  minutely.  This  type  of  homogenizer  has  not  been 
used  much  as  yet  in  the  manufacture  of  evaporated  milk  and 
but  little  is  known  concerning  its  effect  on  this  product. 

In  the  Progress  homogenizer  the  homogenizing  principle 
consists  of  forcing  the  milk,  by  means  of  single  acting  pumps, 
between  a  series  of  discs  with  ground  surfaces.  The  discs  lay 
flat  one  upon  the  other,  they  are  enclosed  in  a  cylinder  and  are 


Fig.  39.     The  Gaulin   homogenizer 
Courtesy   of   Creamery   Package   Mfg.    Company 

held  in  place  by  a  rod  running  through  their  center.  The  discs 
are  pressed  against  each  other  by  a  heavy  spiral  screw,  which 
regulates  the  pressure  to  which  the  milk  is  subjected.  The  milk 
passes  from  the  center  to  the  periphery  of  the  discs.  While  being 
forced  through  the  discs  the  fat  globules  are  split  up  very  finely. 
The  discs  used  in  this  machine  are  of  two  types.  One  type  has 
very  fine  irregular  grooves.  The  milk  shoots  through  these 
grooves  against  hard  shoulders.  The  other  type  of  discs  has 
smooth  surfaces  but  their  area  of  contact  is  narrow.  The  milk 
passes  through  between  these  smooth  surfaces. 


EVAPORATKD    MilyK — HOMOGENIZING  113 

The  Progress  homogenizer  is  used  in  numerous  evaporated 
milk  factories  in  this  country  and,  where  operated  properly,  it 
overcomes  fat  separation  very  satisfactorily,  without  damaging 
the  other  ingredients  of  milk. 

Operation  of  the  Homogenizer.  —  In  order  to  avoid  fat 
separation  it  is  necessary  to  subject  the  milk  to  enough  pressure 
to  reduce  the  fat  globules  to  about  one-third  their  original  size. 
If  enough  pressure  is  applied  to  divide  the  fat  globules  into 
much  smaller  units  there  is  a  tendency  to  also  change  the  prop- 
erties of  the  casein  to  such  an  extent  as  to  cause  it  to  give  rise 
to  copious  precipitation,  when  the  evaporated  milk  is  sterilized, 
and  making  the  finished  product  curdy  and  unmarketable.  In 
this  case  the  cure  would  be  more  disastrous  than  the  original 
defect.  Great  care  must,  therefore,  be  exercised,  guarding 
against  the  use  of  excessive  pressure  that  would  injure  the 
casein.  Experiments  have  shown  that  a  pressure  of  between 
one  thousand  and  fifteen  hundred  pounds  per  square  inch  is 
sufficient  to  prevent  fat  separation  and  is  practically  harmless 
as  far  as  its  objectionable  effect  on  the  casein  in  the  evaporated 
milk  is  concerned. 

The  evaporated  milk  is  run  through  the  homogenizer  hot, 
just  as  it  comes  from  the  vacuum  pan  or  standardizing  tank.  The 
first  pailful  of  milk  passing  through  the  machine  should  be  re- 
turned to  the  supply  tank,  as  on  the  start,  the  pressure  is  not 
uniform  and  homogenization  is  incomplete. 

The  pistons,  cylinders,  valves  and  pipes  of  the  homogenizer 
should  be  kept  in  sanitary  condition.  They  are  difficult  to  clean. 
After  homogenizing,  the  machine  should  be  kept  in  operation, 
running  water  through  it,  until  most  of  the  remnants  of  evap- 
orated milk  are  rinsed  out;  then  hot  water  containing  some 
active  alkali  should  be  pumped  through ;  this  should  be  followed 
by  clean  hot  water  and  steam.  Unless  this  machine  is  kept 
scrupulously  clean,  it  may  become  a  dangerous  source  of  con- 
tamination, infecting  the  evaporated  milk  with  spore  forms  that 
are  exceedingly  resistant  and  which  are  liable  to  pass  into  the 
finished  product  alive,  in  spite  of  the  sterilizing  process,  causing 
the  goods  to  be  a  complete  loss,  due  to  subsequent  fermenta- 
tion. 


314 


EVAPORATED  MILK — COOLING 


CHAPTER  X. 
COOLING 

In  the  cooling  of  the  evaporated  milk,  no  attention  need  be 
paid  to  sugar  crystallization.  In  this  class  of  goods  there  is 
plenty  of  water  to  keep  the  milk  sugar  in  ready  solution.  The 
evaporated  milk  can,  therefore,  be  cooled  as  rapidly  as  facilities 
permit.  The  cooling- 
may  be  accomplished 
in  similar  ways  as 
are  used  for  cooling 
fresh  milk.  From 
the  homogenizer  the 
evaporated  milk  is 
run  over  a  surface 
cooler,  or  cooling 
coil.  It  is  advisable 
to  cover  the  coils 
with  a  jacket  of  gal- 
vanized iron,  tin  or 
copper,  so  as  to  avoid 
undue  contamination 
of  the  milk  from 
dust,  flies,  and  other 

Undesirable       agents.  F'9-   ^Q.     Surface   cooler   for   evaporated    milk 

In       SO-me       COndenS-       Courtesy  of  Davls-Watkins  Dairymen's  Supply  Co. 

cries  the  hot  evap- 
orated milk  is  forced  through  double  pipes,  cold  water  passing 
between  the  inner  and  outer  pipe,  or  the  coils  through  which 
the  milk  passes  are  submerged  in  a  tank  of  cold  water.  The 
only  objection  to  this  system  is  that  the  pipes  are  more  difficult 
to  clean  than  in  the  case  of  an  open  surface  cooler.  Where  this 
system  is  used,  the  pipes  should  be  equipped  with  sanitary  fit- 
tings so  that  they  can  be  readily  swabbed  out  from  both  ends. 
In  other  factories,  the  same  cooling  equipment  is  used  as  for 
sweetened  condensed  milk,  with  the  exception  that  cold  water  is 
run  into  the  cooling  tank  at  once.  In  still  other  factories  the 
cooling  is  done  in  vats  or  tanks  by  means  of  revolving  coils 
which  carry  the  cooling  medium.  If  the  evaporated  milk  is  not 


EVAPORATED  MILK — COOLING 


115 


homogenized  it  should  be  cooled  as  soon  as  it  leaves  the  vacuum 
pan. 

Holding  in  tanks. — The  establishment  and  enforcement  of 
a  Government  standard  of  composition  and  the  tendency  of  the 
manufacturer,  in  the  face  of  increasingly  keen  competition  which 
narrows  down  the  margin  of  profit  and  demands  more  exacting 
attention  to  the  cost  of  manufacture,  to  reduce  his  output  to 
a  uniform  composition  that  complies  with  the  Government 
standard  but  does  not  exceed  it,  have  resulted  in  the  adoption, 
especially  among  the  larger  condenseries  of  the  practice  of 
standardizing  or  unifying  each  day's  output  by  mixing  together 
all  the  batches  of  evaporated  milk  of  one  and  the  same  day's 
make. 

This  practice  necessitates  the  use 
of  one  or  more  large  tanks  with 
facilities  for  refrigeration  of  their 
contents.  This  need  has  been  and  is 
being  admirably  met  by  the  installa- 
tion of  jacketed  glass  enameled  cir- 
cular tanks,  ranging  in  capacity  from 
about  15,000  to  60,000  pounds. 
These  tanks  are  equipped  with 
one  or  more  propellers  which  serve 
to  agitate  the  evaporated  milk,  mix- 
ing it  and  hastening  the  cooling. 
The  propellers  in  the  latest  im- 
proved holding  and  cooling  tanks 
are  located  near  the  side  or  periphery 
of  the  tank  and  are  driven  by  in- 
dependent motor,  or  by  belt  power. 
It  has  been  found  that  the  thus  ex- 
centrically  placed  propeller,  when  set  at  the  proper  angle,  is 
more  efficient  in  its  agitation  and  in  bringing  all  portions  of  the 
evaporated  milk  in  direct  contact  with  the  cooling  jacket  than 
is  the  case  with  the  centrally  located  vertical  agitator,  which 
merely  gives  the  contents  of  the  tank  a  circular  motion. 

In  factories  where  these  large  glass  tanks  are  installed,  each 
successive  batch  of  evaporated  milk  is  transferred,  at  the  con- 
clusion of  the  process  of  evaporation  and  homogenization,  to 


Fig.    42.       Holding    tank    for 

evaporated   milk 
Courtesy  of  The  Pfaudler  Co. 


116 


EVAPORATED  MII.K — FUSING 


this  large  holding  and  cooling  tank,  where  all  the  batches  of  the 
same  days'  make  are  cooled,  mixed  and  held  until  the  last  batch 
is  in  the  tank.  The  mixture  is  then  standardized  to  the  desired 
composition  by  the  addition  of  distilled  water,  skim  milk,  or 
cream,  according  to  needs.  The  evaporated  milk  in  this  tank  is 
usually  cooled  to  and  held  at  40  to  45  degrees.  F.  until  next 
morning,  when  the  filling  into  tins  commences.  See  also  "Stan- 
dardization," Chapter  XXXIX,  page  253. 

It  should  be  understood 
that,  at  this  stage  of  the 
process  the  evaporated  milk 
is  not  sterile,  nor  does  it  con- 
tain cane  sugar  to  preserve 
it,  neither  is  it  sufficiently 
concentrated  to  be  preserved 
because  of  the  absence  ot 
moisture.  If  exposed  to  heat, 
such  as  summerheat,  or  even 
room  temperature,  its  acidity 
will  increase  rapidly  thereby 
rendering  the  subsequent 
sterilizing  process  difficult.  Fig'  41"  Hand0Sl'end9  ™kchlne  for  evap' 

Therefore,      Unless      it      is  Courtesy  of  Arthur  Harris  &   Co. 

canned  and  sterilized  im- 
mediately after  it  leaves  the  vacuum  pan,  or  the  homogenizer  in 
case  it  is  homogenized,  it  should  be  cooled  promptly  to  a  tem- 
perature low  enough  to  check  bacterial  development,  40  to  45°  F., 
or  below.  In  the  absence  of  holding  tanks  or  vats  with  refrigerat- 
ing facilities  as  described  above,  the  cooled  evaporated  milk  may 
be  drawn  into  40  quart  milk  cans,  and  set  in  the  cold  room,  or 
these  cans  may  be  submerged  in  a  tank  of  ice  water. 

FILLING 

The  cooled  evaporated  milk  is  filled  into  tin  cans  ranging  in 
size  from  eight  ounces  to  one  gallon.  The  gallon  cans  are  usually 
filled  by  hand.  The  filling  of  the  smaller  cans  is  done  by  auto- 
matic filling  machines. 

Of  late  years  much  progress  has  been  made  in  the  con- 
struction of  different  types  of  filling  machines  for  evaporated 


EVAPORATED  MILK — FILLING 


117 


milk.  The  opening's  in  the  cans  through  which  the  cans  are 
filled  range  from  the  San- 
itary can,  which  is  filled 
with  the  top  of  the  can 
entirely  removed,  to  the 
venthole  can  with  an 
opening  of  not  more  than 
one-eighth  inch  in  dia- 
meter. The  filling  ma- 
chines are  constructed  to 
fill  by  gravity,  under  pres- 
sure, or  in  vacuo. 

These  filling  machines 
should  be  thoroughly 
washed  and  freed  from  all 
remnants  of  evaporated 
milk  adhering  to  the 
valves  and  other  parts 
after  each  use.  Remnants 
of  milk  left  in  any  part 
of  the  filling  machine 
decompose  readily  and 
impair  the  wholesomeness 
and  marketable  properties  of  the  product.  This  is  an  important 
point  and  one  too  often  neglected.  Much  of  the  spoiled  evap- 
orated milk  may  be  the  result  of  the 
use  of  unsanitary  and  unclean  filling 
machines.  The  fact,  that  the  evap- 
orated milk  is  sterilized  after  it  leaves 
the  filling  machine,  is  no  excuse  for 
unclean  filling  machines.  The  operator 
should  bear  in  mind  that  the  milk  run- 
ning through  an  unclean  filling  ma- 
chine becomes  contaminated  with  mil- 
lions of  bacteria.  The  more  bacteria 
it  contains,  the  more  difficult  it  is  to 
render  it  perfectly  sterile.  Furthermore, 
sporeforms  are  prone  to  develop  in  Fig.  44.  venthole  can 
the  decaying  remnants  of  milk;  these  F  G  Dickerson  Company 


Fig.    43.     Venthole    filling    machine 
Courtesy  of  F.  G.  Dickerson  Company 


118  EVAPORATED  MILK — SEALING 

spores  are  very  resistant  and  require  excessively  high  sterilizing 
temperatures  to  be  destroyed. 

In  the  filling  of  the  venthole  cans  the  foaming  of  the  evapo- 
.  rated  milk  frequently  causes  serious  annoyance.  This  can  be 
avoided  by  having  the  milk  at  the  proper  temperature  at  the  time 
of  filling.  Experience  has  shown  that  warm  milk  and  milk 
excessively  cold  are  most  apt  to  foam  profusely.  Under  average 
conditions,  milk  at  a  temperature  of  60  to  70°  F.  generates  the 
least  amount  of  foam  and  at  this  temperature  the  filling  is  ac- 
complished most  readily. 

SEALING 

The  filled  cans  should  be  capped  and  sealed  at  once.  The 
seal  must  be  hermetical  and  strong  enough  to  withstand  the 
strain  of  the  subsequent  sterilizing  process.  With  the  exception 
of  the  " Sanitary  can,"  seals  without  solder  have  so  far  proven 
unsatisfactory  in  the  canning  of  evaporated  milk.  They  are 
prone  to  weaken  in  the  sterilizer  and  cause  "leakers."  Most  of 
the  cans  on  the  market  containing  evaporated  milk  are,  therefore, 
sealed  with  solder.  Sealing  evaporated  milk  cans  with  solder  is 
by  far  the  safest  method.  For  details  of  methods  of  sealing 
see  Chapter  VII. 

For  the  sealing  or  tipping  of  the  venthole  cans  an  automatic 
tipper  is  usually  attached  to  the  filling  machine,  so  that  when 
the  cans  leave  the  filling  machine,  they  have  also  been  sealed. 

It  is  exceedingly  important  that  the  sealing  be  done  per- 
fectly, because  the  minutests  leaks  cause  the  evaporated  milk  in 
the  cans  to  become  contaminated  causing  spoilage.  In  order  to 
detect  cans  with  imperfect  seals  all  the  cans,  as  they  come  from 
the  filling  and  sealing  machine,  are  carefully  inspected  for  leaks. 
This  may  be  done  by  the  use  of  a  test  bath  consisting  of  a  narrow 
oblong  trough,  filled  with  hot  water  and  through  which  the  cans 
pass  on  an  endless  chain.  In  the  case  of  leaky  cans,  the  heat  ol 
the  hot  waterbath  expands  the  air  in  the  cans  and  causes  it  to 
escape  through  the  leak  in  the  seal  and  perculate  upward  in  the 
water  in  the  form  of  air  bubbles.  The  operator  standing  over 


EVAPORATED  MILK — SEAUNG  119 

the  test  trough  picks  the  cans  which  expel  air  bubbles  out  so 
that  the  defective  seals  can  be  mended. 

Most  condenseries  manufacturing  evaporated  milk  are  now 
using  a  hot  water  bath  for  testing  the  sealed  cans.  But  experience 
has  shown  that  the  hot  water  baths  built  on  the  continuous 
chain  principle  often  fails  to  give  the  desired  efficiency.  This  is 
not  the  fault  of  the  machine,  but  it  is  due  to  the  fact  that  it 
becomes  very  tiresome  for  the  inspector  to  watch  the  moving 
line  of  cans  in  the  water  bath  and  he  soon  becomes  careless  and 
his  work  inefficient.  It  has  been  found  that  baths  constructed 
and  operated  on  the  principle  of  submerging  a  whole  tray  full 
of  cans,  (usually  24  cans)  at  a  time,  give  more  satisfactory  re- 
sults, relieving  the  monotony  and  preserving  more  successfully 
the  keenness  of  observation  of  the  inspector. 

The  venthole  filler  is  simple  in  construction,  economical  in 
operation  and  easily  cleaned  and  kept  in  sanitary  condition.  The 
milk,  from  the  time  it  comes  within  the  range  of  the  filler,  is  no 
longer  exposed  to  contaminating  influences,  such  as  the  hands  of 
employes,  insects,  etc.  The  cans  are  uniformly  filled  to  within  one 
gram  of  the  guaranteed  weight  and  the  vents  or  pin  holes  are 
automatically  sealed  with  the  minimum  amount  of  solder.  While 
the  quantity  of  solder  must  necessarily  vary  with  operating 
conditions,  it  is  possible  to  limit  the  average  amount  of  solder, 
under  proper  conditions,  to  5  ounces  per  1000  cans.  The  fact 
that  the  vent  hole  or  pin  hole  filler  operates  by  gravity,  as  to 
both,  the  empty  cans  and  the  inflowing  evaporated  milk,  reduces 
the  human  and  mechanical  error  to  the  minimum,  once  the 
machine  is  set  for  operation. 

The  acknowledged  advantages  of  the  venthole  filler  have 
made  its  general  adoption  and  use  rapid  and  it  is  estimated  that 
today  over  90  per  cent  of  the  evaporated  milk  is  being  canned 
by  this  type  of  filling  machine. 


120  EVAPORATED  MILK — STERILIZING 

CHAPTER  XL 
STERILIZING 

The  sealed  cans  are  now  ready  for  the  sterilizer.  If  they 
cannot  be  sterilized  within  an  hour  or  two  they  should  be  sub- 
merged in  ice  water  or  placed  in  a  refrigerating  room  until  the 
sterilizer  is  ready  for  them.  This  precaution  is  especially  ad- 
visable in  summer. 

Purpose  of  Sterilization. — The  chief  purpose  of  subjecting 
the  evaporated  milk  to  the  sterilizing  process  is  to  kill  all  germ 
life  and,  therefore  preserve  the  product  permanently.  When  the 
hermetically  sealed  cans  come  from  the  sealing  room,  their 
contents  are  not  sterile.  The  only  means  to  preserve  this  milk 
is  to  subject  it  to  temperatures  high  enough  to  kill  all  forms  of 
ferments,  organized  and  unorganized,  vegetative  cells  and  spores. 
The  success  of  the  manufacture  of  this  product  depends  to  a 
large  extent  on  the  process  of  sterilization. 

Aside  from  this,  the  manufacturer  aims  to  gain  another  com- 
mercially important  condition,  namely,  to  prevent  the  separation 
of  the  butter  fat.  Before  sterilization,  there  is  nothing  to  prevent 
the  fat  from  separating  out  in  the  evaporated  milk  and  from 
churning  in  transportation,  unless  the  evaporated  milk  was 
homogenized.  This  is  a  highly  undesirable  characteristic,  mak- 
ing the  goods  unmarketable.  The  sterilizing  process  helps  to  so 
change  the  physical  properties  of  the  milk,  that  this  tendency 
of  the  fat  to  separate  is  greatly  minimized.  The  sterilizing 
temperatures  used,  further  lend  to  the  evaporated  milk  a  creamy 
consistency  and  yellowish  color,  giving  the  product  a  semblance 
of  richness. 

Sterilizers.  —  The  predomi- 
nating apparatus  used  for  ster- 
ilizing is  a  huge,  boiler-like, 
hollow,  iron  cylinder  or  box. 
It  opens  either  at  one  end 
or  on  the  side.  Its  interior 
is  equipped  with  a  revolving 
framework,  steam  inlet  and  ex- 
haust,  a  water  distributing  pipe 
running  the  entire  length  of 


EVAPORATKD  MILK — STERILIZING 


121 


the  sterilizer  and  a  water  exhaust.  The  sterilizer  carries  on  its 
exterior  a  steam  gauge,  a  vacuum  gauge,  a  water  gauge,  a  blow- 
off  valve  and  a  high-temperature  thermometer  (registering  to 
about  280  degrees  F.).  In  some  makes  of  sterilizers  the  interior 
frame-work  does  not  revolve  on  its  axis,  but  moves  back  and 

forth  by  means 
of  a  direct-act- 
ing, steam- 
driven  piston, 
attached  to  the 
back  end  of  the 
sterilizer.  The 
purpose  of 
keeping  the 
cans  in  motion 
while  heat  is 
applied,  is  to 
heat  the  coti- 
tents  rapidly 
and  unifonn|ly, 
and  to  prevent 
the  evaporated 
milk  from  bak- 
ing onto  the 
sides  of  the 
cans.  A  still 

other  form  of  sterilizer  is  the  continuous  sterilizer  in  which  the 
unsterilized  cans  pass  into  and  the  sterilized  cans  escape  from 
the  heating  chamber  in  continuous  procession. 

Loading  the  Batch-Sterilizer. — The  sealed  tin  cans  are  placed 
in  heavy  iron  trays,  usually  holding  twenty-four  16-ounce  cans  or 
six  1-gallon  cans.  The  loaded  trays  are  slid  and  locked  into  the 
framework  in  the  interior  of  the  sterilizer.  The  sterilizer  is  closed 
with  heavy  iron  doors  and  the  frameAvork  is  put  in  motion.  In 
some  makes  of  sterilizers  the  interior  consists  of  a  large  per- 
forated iron  box  revolving  on  its  axis.  In  this  case  the  cans  are 
simply  piled  into  this  box;  no  trays  being  used. 

Uniform  Distribution  of  Heat. — Where  no  water  is  used  in 
the  sterilizer  during  the  sterilizing  process,  it  is  important  that 


Fig.    46.     Sterilizer   for    evaporated    milk 
Courtesy   of   The   Engineering  Company 


122  EVAPORATED  MILK — STERILIZING 

there  be  a  free  air  space  between  every  two  layers  of  cans,  so  as 
to  allow  the  steam  to  circulate  freely  and  to  come  in  direct  con- 
tact with  every  can.  When  the  cans  are  piled  into  the  sterilizer 
six  to  twelve  layers  deep  without  any  free  air  space  between 
layers,  the  cans  in  the  center  do  not  receive  as  much  heat  as  those 
at  the  sides,  ends,  top  and  bottom.  This  causes  irregular  heating 
and  imperfect  sterilization. 

A  satisfactory  means  of  insuring  even  distribution  of  heat 
is  to  fill  the  sterilizer  about  one-thirdful  of  water,  so  that,  when 
the  sterilizer  is  in  operation  the  cans  pass  through  this  water, 
with  each  revolution  of  the  frame  work.  Water  distributes  the 
heat  uniformly,  rapidly  and  there  is  no  danger  of  the  formation 
of  air  pockets  between  the  cans.  Since  the  heat  is  applied  by 
steam  under  pressure  the  temperature  of  the  water  is  equal  to 
that  of  the  steam  in  the  sterilizer.  This  precaution  is  especially 
necessary  in  the  case  of  baby-size  cans  (eight  ounces)  which  are 
usually  piled  in  stacks  more  than  two  deep.  When  sterilizing 
in  the  absence  of  water  there  is  danger  of  lack  of  uniformity  of 
the  amount  of  heat  they  receive. 

Temperature  and  Time  of  Exposure. — When  the  sterilizer 
is  filled  with  the  cans  and  closed,  the  frame  work  is  set  in  motion 
and  steam  is  turned  into  the  sterilizer.  In  order  to  hasten  the 
heating  and  expel  all  the  air,  the  exhaust  and  safety  should  be 
left  open  until  the  temperature  has  risen  to  212  degrees  F.  This 
temperature  is  usually  reached  in  about  ten  to  fifteen  minutes. 
The  exhaust  and  safety  are  then  closed. 

From  this  point  on,  the  process  must  depend  on  locality, 
season  of  year  and  condition,  properties  and  concentration  of  the 
milk.  No  formula  can  be  laid  down  which  can  be  depended  on 
to  give  uniformly  satisfactory  results  under  all  conditions.  Nor 
does  the  proper  sterilization  depend  on  one  particular  formula. 
There  are  numerous  ratios  of  temperature,  time  of  exposure  and 
extent  of  agitation,  which  when  adjusted  to  local  conditions  may 
give  satisfactory  results.  The  temperature  should  be  high  enough 
and  the  duration  of  exposure  long  enough  to  insure  absolute 
sterility  of  the  product  and  to  give  the  milk  sufficient  body  to 
prevent  the  separation  of  the  butter  fat  in  subsequent  storage. 
The  temperature  should  not  be  so  high  nor  the  duration  of  ex- 


EVAPORATED  MILK — STERILIZING  123 

posure  so  long,  as  to  cause  the  formation  of  a  hard,  unshakable 
curd  and  dark  color. 

Some  processors  use  a  very  short  process  with  high  tempera- 
tures, others  raise  the  heat  gradually  and  not  to  quite  so  high  a 
degree.  The  more  gradual  heating  is  preferable,  as  it  gives  the 
product  a  better  body  and  more  viscosity,  which  is  necessary  to 
keep  the  fat  from  separating  in  storage.  The  author's  judgment 
in  this  matter  is,  that  it  is  not  safe  to  raise  the  temperature  to 
less  than  230  degrees  F.  and  it  is  advisable  to  heat  the  milk  to 
234  to  236  degrees  F.,  provided  that  the  milk  is  in  condition  to 
stand  this  heat  without  the  formation  of  too  firm  a  curd.  Where 
the  maximum  temperature  to  which  the  milk  is  raised  in  the 
sterilizer  is  230  degrees  F.  or  thereabout,  the  raise  of  the  last  ten 
degrees  should  occupy  from  thirty-five  to  forty-five  minutes,  and 
this  time  should  be  about  evenly  distributed  over  the  last  ten 
degrees. 

Of  recent  years,  the  practice  of  stopping  the  reel  of  the 
sterilizer,  either  at  intervals  or  when  the  maximum  temperature 
has  been  reached,  has  been. adopted  by  some  of  the  manufacturers. 
In  this  case,  the  temperature  usually  is  rapidly  raised  to  about 
240°  F.,  and  after  keeping  the  reel  running  at  this  temperature 
for  a  few  minutes  (about  two  minutes)  the  reel  is  stopped  and 
this  temperature  is  maintained  for  from  15  to  20  minutes,  with 
the  cans  laying  still.  When  the  "hold"  is  completed,  the  cooling 
proceeds  in  the  usual  way.  Some  condenseries  stop  the  reel  for 
several  minutes  once  or  twice  when  the  temperature  has  been 
lowered  and  before  it  has  dropped  to  below  212°  F. 

This  method  of  sterilizing,  by  stopping  the  reel,  has  the 
advantage  of  developing  in  the  cans  a  soft,  custard-like  coagu- 
lum,  giving  the  product  a  very  heavy  consistency  and  making  it 
appear  rich  and  creamy.  It  represents  a  form  of  superheating, 
however,  which  if  not  done  with  great  care,  may  prove  disastrous, 
causing  the  evaporated  milk  to  spontaneously  thicken  and  become 
cheesy  in  consistency  upon  storage. 

In  his  efforts  to  insure  complete  sterility  the  operator  should 
understand  that  the  size  of  the  cans  may  influence  the  sterilizing 
efficiency.  It  takes  more  time  and  agitation  to  sterilize  gallon 
cans  than  small  cans.  At  a  time  of  the  year  when  the  milk  con- 
tains micro-organisms  of  relatively  high  resistance  to  heat,  as 


124  EVAPORATED  MILK — STERILIZING 

is  often  the  case  especially  in  fall  and  winter,  the  per  cent  loss 
of  gallon  cans  due  to  "swell  heads"  may  become  disastrously 
large,  unless  the  manufacturer  makes  a  special  effort  to  adjust  his 
process  for  gallon  cans. 

The  installation  and  efficient  use  of  automatic  temperature 
controllers  and  recorders  is  of  material  assistance  for  securing 
uniform  results  of  sterilization.  These  accessories  are  made  use 
of  in  numerous  factories,  and  have  proven  to  be  of  valuable  help 
to  the  manufacturer.  Aside  from  the  fact  tha-t  they  actually  do 
facilitate  the  temperature  control,  they  automatically  make  for 
increased  efficiency  of  the  operator.  The  knowledge  of  the 


Fig.  47.     Pilot  sterilizer 
Courtesy   of   The   Engineering   Company 

operator  that  his  work  is  permanently  recorded  and  checked  up 
exerts  a  beneficial  effect  on  his  performance. 

The  operation  of  an  experimental  or  pilot  sterilizer  also  has 
proven  a  great  help  in  the  accurate  determination  of  the  amount 
of  heat  which  the  evaporated  milk  of  any  batch  requires,  to 
produce  the  desired  viscosity,  body  and  color  and  that  it  will 
stand  without  becoming  hopelessly  curdy.  These  machines  are 
of  small  size,  accomodating  only  a  feAv  cans. 

A  few  sample  cans  of  each  batch  are  placed  in  the  pilot 
sterilizer  and  run  through  the  process.  Thus  the  proper  process 


EVAPORATED  MILK — STERILIZING  125 

to  be  used  for  the  entire  batch  in  the  large  sterilizer  may  be 
adjusted  according  to  the  behavior  of  the  contents  of  the  sample 
cans  in  the  pilot  sterilizer. 

Qualifications  of  the  Processer. — The  operator,  or  the  person 
directing  the  sterilizing  process,  should  thoroughly  appreciate 
the  complexity  of  the  product,  understand  the  cause  and  effect 
of  the  many  influencing  factors,  study  the  ever-changing  condi- 
tions and  modify  the  process  in  accordance  with  prevailing  con- 
ditions. He  should  know  that  during  the  exceedingly  hot  sum- 
mer days,  when  the  cows  suffer  from  heat  and  are  pestered  with 
flies,  the  milk  will  not  stand  as  much  heat  without  badly  curdling 
in  the  sterilizer  as  under  more  favorable  conditions.  He  should 
know  that  toward  and  during  the  fall  months  the  organisms 
normally  present  in  milk  are  more  resistant  and  require  higher 
heat  to  be  destroyed,  than  earlier  in  the  season. 

Rapid  and  Uniform  Cooling. — As  soon  as  the  required  heat 
has  been  given  the  milk  in  the  sterilizer,  the  steam  should  be 
turned  off  and  the  exhaust  and  drain  should  be  opened.  When 
the  temperature  has  dropped  to  about  220  degrees  F.,  cold  water 
should  be  turned  into  the  sterilizer  while  the  cans  are  constantly 
in  motion,  until  the  cans  are  cool  enough  to  handle.  There  should 
be  enough  cold  water  available  to  reduce  the  temperature  to  70 
or  80  degrees  F.  in  twenty  minutes  for  gallons  and  in  ten  to 
fifteen  minutes  for  small  size  cans.  The  water  pipe  should  be 
so  arranged  as  to  distribute  the  water  uniformly  over  the  entire 
length  of  the  sterilizer. 

If  the  process  is  to  be  sucessful,  the  processor  must  have  as 
nearly  perfect  control  of  the  heat  as  possible.  This  means  espe- 
cially, that  there  must  be  plenty  of  water  available  to  insure 
rapid  cooling  and  the  water  must  be  distributed  over  the  cans 
uniformly.  Insufficient  water  supply  and  uneven  distribution 
of  the  water  in  the  sterilizer,  means  that  some  of  the  cans  are 
exposed  to  the  sterilizing  heat  longer  than  others,  causing  lack 
of  uniformity  in  the  smoothness  and  color  of  the  milk  of  different 
cans  of  the  same  batch.  Delayed  cooling,  owing  to  insufficient 
water  supply,  has  the  further  disadvantage  of  causing  the  cans 
to  bulge  badly,  owing  to  the  difference  in  pressure  between  the 
interior  and  exterior  of  the  cans.  This  is  especially  noticeable 
in  gallon-size  cans,  the  ends  of  which  may  become  badly  dis- 


126  EVAPORATED  MILK — SHAKING 

torted,   present   an   unsightly   appearance  and   their   seams   and 
seals  may  be  weakened  to  the  extent  of  producing  "leakers." 

Fractional  Sterilization. — In  the  early  days  of  the  manu- 
facture of  evaporated  milk  the  product  was  sterilized  by  frac- 
tional sterilization.  This  method  has  now  been  largely  abandoned, 
but  is  occasionally  used  when  the  milk  happens  to  be  in  very 
abnormal  condition.  The  milk  is  heated  in  the  sterilizer  to  con- 
siderably lower  temperatures  than  those  stated  above,  and  this 
heating  is  repeated  on  two  or  three  successive  days.  The  prin- 
ciple of  this  process  is  to  kill  all  vegetative  forms  of  bacteria 
during  the  first  heating.  This  gives  the  spores  a  chance  to 
develop  into  vegetative  forms  by  the  second  and  third  days, 
which  forms  are  then  destroyed  during  subsequent  heating.  This 
system  of  sterilization  is  not  practical  for  general  use.  It  is  too 
great  a  tax  on  the  capacity  of  the  average  factory  and  increases 
the  cost  of  manufacture.  It  should,  therefore,  be  made  use  of 
only  in  exceptional  cases,  when  it  is  known  that  a  certain  batch 
of  milk  could  not  be  put  through  the  higher  sterilizing  tem- 
peratures without  causing  the  product  to  become  permanently 
curdy. 

SHAKING 

Purpose. — The  purpose  of  shaking  the  evaporated  milk  is  to 
mechanically  break  down  the  curd  that  may  have  been  formed 
in  the  process  of  sterilization  and  to  give  the  contents  of  the  cans 
a  smooth  and  homogeneous  body. 

The  high  temperatures  to  which  the  evaporated  milk  is  sub- 
jected in  the  sterilizer  have  a  tendency  to  coagulate  the  casein. 
In  the  case  of  normal,  fresh  milk  the  casein  coagulates  at  a  tem- 
perature of  269  degrees  F.  In  the  evaporated  milk,  made  from 
perfectly  normal  and  sweet,  fresh  milk  the  casein  curdles  at  much 
lower  temperatures,  and  the  higher  the  ratio  of  concentration, 
the  lower  the  temperature  required  to  precipitate  the  casein.  It 
seems  that  the  concentration  of  the  milk  intensifies  the  properties 
of  milk  to  coagulate  when  subjected  to  heat.  This  factor  is 
probably  largely,  though  not  necessarily,  wholly  due  to  the  in- 
crease of  the  per  cent  of  lactic  acid  in  the  evaporated  milk,  due 
to  the  concentration.*  If  the  fresh  milk  contains  .17  per  cent 


EVAPORATED  MILK — SHAKING 


127 


lactic  acid,  a  concentration  of  two  and  one-fourth  parts  of  fresh 
milk  to  one  part  of  evaporated  milk  causes  the  evaporated  milk 
to  contain  .17  X  2.25  =  .38  per  cent  lactic  acid.  With  this  amount 
of  acid  acting  on  the  casein,  it  is  not  difficult  to  understand  why 

a  coagulum  is  often  formed  in 
the  sterilizer.  While  the  forma- 
tion of  this  coagulum  may  be 
partly  avoided,  under  certain 
conditions  it  appears  in  every 
factory  and  there  are  more 
batches,  especially  in  summer, 
Fig.  48.  shaker  that  come  from  the  sterilizer 

courtesy  of  Arthur  Harris  &  Co.          coagulated  than  otherwise. 

In  this  condition  the  product  is  not  marketable.  Some  means 
must  be  provided,  therefore,  to  break  up  this  curd  and  reduce 
the  contents  of  the  cans  to  a  smooth,  homogeneous  and  creamy 
body.  For  this  purpose  a  mechanical  shaker  is  used. 


Fig.  49.     Shaker 
Courtesy   of    The    Engineering   Company 

Method  of  Shaking. — The  shaker  consists  of  one  or  more 
heavy  iron  boxes  or  boxes  made  of  black  iron  pipes.  These 
boxes  are  attached  to  an  eccentric.  The  trays  filled  with  evapo- 
rated milk  cans  are  firmly  wedged  into  these  boxres.  When  the 
shaker  is  in  operation,  the  cans  are  shaken  back  and  forth  violent- 
ly, causing  the  curd  in  the  cans  to  be  broken  up. 

Speed  of  the  Shaker. — If  the  shaker  is  to  perform  its  work 
properly,  it  must  have  long  enough  a  stroke  and  run  fast  enough 
to  cause  most  vigorous  agitation.  The  stroke  should  be  not  less 
than  about  two  and  one-half  inches  and  the  eccentric  should  re- 


128  EVAPORATED  MILK — INCUBATING 

volve  not  less  than  three  hundred  to  four  hundred  times  per 
minute.  In  order  to  accomplish  this  without  wrecking  the  ma- 
chine, the  shaker  must  be  fastened  securely  to  a  solid  foundation. 

From  one-fourth  to  two  minutes'  shaking  is  usually  suffi- 
cient to  completely  break  down  a  soft  curd.  When  shaking  for 
five  minutes  does  not  produce  a  smooth  milk,  the  product  is 
usually  hopelessly  curdy  and  no  amount  of  additional  shaking 
will  remedy  the  defect. 

In  some  cases  it  has  been  possible,  however,  to  improve  the 
curdy  product  by  shaking  again  after  a  day  or  two.  Under  cer- 
tain conditions,  age  seems  to  have  a  slight  mellowing  effect  on 
the  curd. 

Efficiency  of  Different  Types  of  Shakers. — Some  shakers 
have  a  straight,  horizontal,  back  and  forth  motion.  Others  have 
a  rotary  or  elliptical  motion;  the  latter  are  not  considered  as 
effective  in  their  work  as  the  former.  Some  of  the  sterilizers  in 
which  the  interior  frame  holding  the  cans,  moves  back  and  forth, 
are  advertised  to  shake  the  milk  as  well  as  sterilize  it.  Ex- 
perience has  shown,  however,  that  the  shaking  performed  by 
these  sterilizer-shakers  is  not  sufficient  and  that  the  use  of  a 
separate  shaker  is  necessary. 

Formation  of  Curd  not  Desirable  nor  Necessary. — It  should 
be  understood  that  the  processor  should  aim  to  get  only  a  very 
slight  and  soft  curd  in  his  product,  that  can  be  shaken  out  in  the 
shaker  in  one-fourth  to  one-half  minute.  When  the  curd  prod- 
uced is  firm,  even  prolonged  shaking  will  not  prevent  the  appear- 
ance in  the  finished  product  of  specks  and  small  lumps  of  curd. 
Such  milk  is  rejected  on  the  market. 

The  formation  of  curd  during  the  sterilizing  process  is  not 
desirable  and  is  not  necessary  as  far  as  the  marketable  properties 
of  the  evaporated  milk  is  concerned.  It  is  unavoidable,  however, 
under  many  conditions  and  as  long  as  it  can  be  confined  to  a  soft 
curd  that  readily  shakes  out,  no  harm  is  done. 

INCUBATING 

From  the  shaker,  the  cans  are  transferred  to  the  incubating 
room.  This  is  a  room  with  a  temperature  of  70  degrees  to  90 
degrees  F.  The  evaporated  milk  remains  there  ten  to  thirty  days. 


PLAIN  CONDENSED  BULK  MILK  129 

The  purpose  of  incubation  is  to  detect  defective  milk  and  de- 
fective cans  before  they  leave  the  factory.  If  the  contents  of 
any  of  the  cans  have  not  been  completely  sterilized,  or  if  any 
cans  have  the  minutest  leak,  the  evaporated  milk  therein  will 
spoil  within  the  time  of  incubation.  Such  milk  either  sours, 
curdles  or  becomes  solid,  or  it  undergoes  gaseous  fermentation, 
causing  the  appearance  of  "swell  heads."  The  more  nearly  perfect 
the  process  of  sterilization  and  the  better  the  construction  and 
seal  of  the  cans,  the  fewer  are  the  spoiled  cans.  This  incubation 
process  is  strictly  a  preventative  measure.  It  is  omitted  in  many 
factories  where  the  cans  are  labeled,  packed  and  shipped  to  their 
destination  at  once,  or  put  in  ordinary  storage  in  the  factory. 


CHAPTER  XII. 
PLAIN  CONDENSED  BULK  MILK 

Definition. — This  is  an  unsweetened  condensed  milk  made 
from  whole  milk,  or  partly,  or  wholly  skimmed  milk,  condensed 
in  vacuo  at  the  ratio  of  about  three  or  four  parts  of  fluid  milk  to 
one  part  of  condensed  milk.  It  is  usually  superheated  to  swell 
and  thicken  it,  and  it  has  the  consistency  of  rich  cream.  It  is 
sold  in  10-gallon  milk  cans  to  ice  cream  factories  and  in  milk 
bottles  to  the  direct  consumer.  Plain  condensed  bulk  milk  is 
not  sterile,  nor  is  it  preserved  by  sucrose.  Its  keeping  quality 
is  similar  to  that  of  a  high  quality  pasteurized  milk. 

Quality  of  Fresh  Milk. — The  sweeter  and  purer  the  fresh 
milk  or  skim  milk,  the  better  will  be  the  quality  of  this  product. 
Old  milk,  or  skim  milk  in  which  the  acid  development  has  made 
considerable  headway,  tends  to  form  a  lumpy,  plain  condensed 
bulk  milk.  However,  since  this  milk  is  not  subjected  to  steriliz- 
ing temperatures  and  is  used  up  quickly  after  manufacture,  the 
quality  of  the  fresh  milk  from  which  it  is  made,  is  not  of  such 
magnitude  as  in  the  case  of  evaporated  milk. 

Heating. — In  the  manufacture  of  plain  condensed  bulk  milk 
the  heating  is  accomplished  much  in  the  same  manner  as  in  the 
case  of  sweetened  condensed  milk  and  evaporated  milk.  The 
milk  is  usually  heated  by  turning  steam  direct  into  it ;  though 


130  PLAIN  CONDENSED  BULK  MILK 

many  of  the  more  efficient  types  of  milk  and  cream  pasteurizers 
could  be  used  to  excellent  advantage  for  this  purpose. 

It  is  advisable,  however,  to  heat  this  milk  only  to  about  150 
to  160  degrees  F.  in  order  to  secure  a  nice  "liver"  (coagulum), 
when  it  is  superheated  in  the  pan.  If  the  milk  is  heated  to  the 
boiling  point  in  the  forewarmers,  it  does  not  respond  to  the  super- 
heating in  the  pan  as  satisfactorily. 

Condensing. — The  condensing  of  plain  condensed  bulk  milk 
is  done  in  the  vacuum  in  a  similar  manner  as  described  under 
evaporated  milk,  except  that  the  evaporation  is  carried  farther. 
See  also  Chapter  XIV  on  "The  Continuous  Concentrator,"  pages 
133  to  141. 

Superheating. — When  the  condensation  is  nearly  completed 
the  milk  in  the  pan  is  superheated.  This  is  accomplished  by 
shutting  off  the  steam  to  the  jacket  and  coils,  closing  the  valve 
that  regulates  the  water  supply  of  the  condenser,  stopping  the 
vacuum  pump  and  blowing  steam  direct  into  the  milk  in  the  pan, 
for  the  purpose  of  swelling  and  thickening  it.  During  this 
process  the  temperature  rises  to  between  180  and  200  degrees 
F.  When  the  milk  has  become  sufficiently  thick  or,  in  the  lan- 
guage of  the  processor,  has  produced  the  "proper  liver"  (coagu- 
lum) the  steam  is  shut  off,  water  is  again  turned  into  the  con- 
denser and  the  vacuum  pump  is  started  up.  As  soon  as  the 
vacuum  has  risen  to  from  twenty-five  to  twenty-six  inches  and 
the  temperature  has  dropped  to  about  130  degr.  F.  the  process  is 
complete,  the  vacuum  is  released  and  the  condensed  milk  is 
drawn  off.  The  superheating  usually  occupies  about  twenty-five 
to  thirty  minutes. 

The  completion  of  the  superheating,  or  the  point  when  the 
superheating  should  cease,  may  also  readily  be  detected  by  the 
examination  of  a  sample  of  the  product.  As  soon  as  the  con- 
densed milk  begins  to  show  a  flaky  condition  of  the  curd,  the 
purpose  of  superheating  has  been  accomplished.  The  amount  of 
superheating  necessary  and  that  the  milk  will  stand,  will  largely 
depend,  aside  from  the  sweetness  of  the  original  milk,  on  the 
extent  of  the  concentration.  The  higher  the  ratio  of  concentra- 
tion, the  less  superheating  is  required  to  secure  the  desired 
results. 


PLAIN  CONDENSED  BULK  MILK  131 

Striking. — The  striking-,  or  sampling  and  testing  for  gravity 
is  done  with  a  Beaume  hydrometer,  the  same,  or  a  similar  one, 
as  is  used  for  evaporated  milk.  The  scale  should  extend  to  15 
degrees  Beaume.  The  batch  should  be  struck  before  and  after 
superheating. 

Factories  which  standardize  their  product  to  a  certain 
established  density,  usually  condense  the  milk  to  a  point  slightly 
beyond  that  desired.  Then,  after  superheating,  they  determine 
the  amount  of  water  required  to  reduce  the  finished  product,  and 
then  add  the  required  amount  of  water  before  the  condensed  milk 
is  cooled.  It  is  advisable  to  use  distilled  water  for  this  purpose. 

Ratio  of  Concentration. — The  ratio  of  concentration  varies 
largely  with  the  fat  content  of  the  milk,  although  the  locality 
and  season  of  year  are  also  influencing  factors.  Whole  milk  is 
condensed  at  the  ratio  of  about  three  parts  of  milk  to  one  part  of 
condensed  milk,  while  the  ratio  of  concentration  for  skim  milk 
is  about  4  to  1.  The  proper  density  varies  somewhat  with  locality 
and  season  of  year.  Roughly  speaking,  whole  milk  has  reached 
the  proper  density  when  the  Beaume  reading  at  120  degrees  F. 
is  about  10  degrees  B.  and  skim  milk  has  reached  about  the 
proper  density  when  the  Beaume  reading  at  120  degrees  F.  is 
about  14  degrees  B.  When  the  ratio  of  concentration  exceeds 
4  to  1,  there  is  danger  of  gritty  condensed  milk  due  to  the  pre- 
cipitation, in  this  concentrated  product,  of  crystals  of  milk  sugar. 

Cooling. — The  plain  condensed  bulk  milk  is  usually  drawn 
into  40  quart  milk  cans,  placed  in  cooling  tanks  containing  re- 
volving cogwheels,  as  described  in  Chapter  VI,  under  "Cooling 
Sweetened  Condensed  Milk,"  and  is  cooled  to  as  near  the  freezing 
point  as  facilities  permit. 

Recently  this  crude  and  laborious  method  of  cooling  has 
been  superseded  in  many  of  the  larger  condenseries  by  more 
modern  ways.  While  the  plain  condensed  bulk  milk  becomes 
too  thick  and  sluggish  during  the  process  of  cooling  to  make 
possible  the  use  of  surface  coolers,  and  internal-tube  coolers,  it 
can  be  readily  cooled  in  vats  equipped  with  revolving  discs,  or 
in  horizontal  coil  vats  especially  constructed  for  this  purpose 
and  in  which  the  lower  part  of  the  vat  is  constricted  and  the  coil 
sets  very  low  in  this  constricted  part,  so  as  to  agitate  the  milk 
vigorously  and  at  the  same  time  prevent  the  incorporation  of  air, 


132  CONCENTRATED  MILK 

by  being  completely  submerged,  or  in  circular  vats  equipped 
with  a  vertically  suspended  coil.  The  vertical  coil  vat  has  the 
further  advantage  in  that  it  eliminates  from  the  milk,  all  bear- 
ings and  glands  and  it  expells,  rather  than  incorporates  air, 
from  the  condensed  milk. 

When  cooled  the  condensed  milk  is  ready  for  the  market. 
If  held  in  the  factory,  it  should  be  placed  in  a  cold  room  or  should 
be  otherwise  protected  against  temperatures  sufficiently  high  to 
cause  it  to  sour.  When  kept  at  40°  F.  or  below  the  danger  from 
souring  is  largely  eliminated.  If  transported  long  distances  during 
warm  weather,  it  should  be  shipped  in  refrigerator  cars. 

CHAPTER  XIII. 
CONCENTRATED  MILK 

Definition. — Concentrated  milk  is  cow's  milk,  either  whole 
milk,  or  partly  or  wholly  skimmed  milk,  condensed  at  the  ratio 
of  three  to  four  parts  of  fresh  milk  to  one  part  of  concentrated 
milk.  It  is  not  condensed  in  vacuo,  but  in  open  vats  by  passing 
currents  of  hot  air  through  the  milk.  It  is  sold  largely  in  pint 
and  quart  bottles  for  direct  consumption.  It  is  not  sterile  and 
therefore  keeps  for  a  limited  time  only.  Its  keeping  quality  is 
similar  to  that  of  a  high  grade  of  properly  pasteurized  milk.  The 
process  by  which  the  concentrated  milk  is  manufactured  is 
known  as  the  "Campbell  Process."  This  process  was  invented 
by  J.  H.  Campbell  of  New  York  City,  in  1900  and  patented  in 
1901. 

Apparatus  Needed. — The  principal  parts  are :  the  evap- 
orating vat  with  hot  water  jacket  and  coils,  and  air  blast  registers 
or  nozzles  near  the  bottom  of  the  vat ;  an  air  blower  which 
fxirnishes  the  air  blast;  an  air  heater  through  which  the  air 
blast  passes  and  from  which  the  heated  air  is  conducted  into  the 
milk;  a  water  pump  circulating  hot  water  through  the  jacket  and 
coils ;  an  auxiliary  evaporating  tank  for  completing  the  evapora- 
tion ;  and  a  spray  pump  which  throws  the  spray  of  milk  drawn 
from  the  bottom  of  the  main  evaporating  vat  into  the  auxiliary 
tank  and  for  transferring  the  partly  condensed  milk  from  tank  1 
to  tank  2. 

Operation  of  Campbell  Process. — The  milk  is  heated  to  about 
100  degrees  F.  and  allowed  to  flow  into  evaporating  tank  1 


CONTINUOUS  PROCESS  EVAPORATORS  133 

Water  at  temperatures  ranging-  from  100  to  125  degrees  F.  is 
forced  through  the  coils  and  jacket.  Hot  air  is  then  passed  into 
the  milk.  The  temperature  of  the  air  is  regulated  so  as  to  keep 
the  temperature  of  the  evaporating  milk  down  to  120  degrees  F. 
on  the  start,  and  to  finish  the  evaporation  between  90  and  100 
degrees  F.  The  air  blast  is  so  introduced  as  to  keep  the  milk 
along  the  heating  surface  of  the  jacket  and  coils  in  circulation 
and,  therefore,  prevent  largely  the  baking  of  the  milk  on  the 
heating  surface.  After  the  milk  has  been  evaporated  to  a  certain 
degree  of  concentration,  say  2:1,  it  is  transferred  to  the  auxiliary 
evaporating  tank  where  the  condensation-  is  completed.  This 
transfer  is  not  necessary,  but  is  resorted  to  solely  as  a  conven- 
ience, in  order  to  continue  treatment  of  the  reduced  bulk  of 
material  in  a  smaller  tank  and  leave  the  larger  tank  free  for 
treating  a  fresh  batch  of  milk,  and  further,  because  there  are 
no  obstructing  coils  in  the  auxiliary  tank,  interfering  with  the 
drawing  off  of  the  finished  and  thick  condensed  milk.  In  this  pro- 
cess, as  now  used,  the  milk  is  usually  first  separated  and  the 
skim  milk  only  is  condensed.  The  cream  is  subsequently  added, 
to  the  condensed  skim  milk. 

Advantages  and  Disadvantages  of  Campbell  Process. — The 
initial  cost  of  installing  the  necessary  machinery  is  much  less 
than  where  vacuum  evaporation  is  practiced.  The  low  heat 
applied  makes  it  possible  for  the  finished  product  to  retain  the 
properties  of  raw  milk,  leaving  the  albumenoids  and  lime  salts 
in  their  original  and  easily  digestible  form. 

This  process  is  applicable  only  in  the  manufacture  of  un- 
sweetened condensed  milk.  Unless  subsequently  sterilized,  the 
product  will  fceep  for  a  short  time  only.  This  process  has  at  the 
present  time  only  very  limited  use.  It  can  hardly  be  considered 
as  an  important  branch  of  the  condensed  milk  industry. 

CHAPTER  XIV. 
CONDENSING  MILK  BY  CONTINUOUS  PROCESS 

The  processes  of  condensing  milk  described  in  preceding 
chapters,  are  exclusively  confined  to  the  intermittent  or  batch- 
principle  of  evaporation.  That  is  in  the  case  of  the  vacuum  pan. 
the  fresh  milk  runs  into  the  pan  until  the  capacity  of  the  pan  is 
reached  and  no  condensed  milk  leaves  the  pan  until  the  condensa- 


134  CONTINUOUS  PROCESS  EVAPORATORS 

tion  of  the  entire  batch  is  completed.  Then  the  pan  must  be 
emptied  before  more  milk  can  be  drawn  in.  In  a  similar  man- 
ner, in  the  Campbell  process,  evaporation  of  the  entire  batch 
must  be  completed  before  any  of  the  finished  product  leaves  the 
evaporating  vat  or  tank.  The  operation  in  either  case  is  inter- 
mittent and  not  continuous. 

Of  more  recent  years,  equipment  and  processes  have  been 
developed  that  make  possible  continuous  operation.  That  is  the 
fresh  milk  enters  the  machine  and  the  condensed  milk  leaves  it 
simultaneously  and  continuously.  So  far  two  types  of  continuous 
machines  have  been  perfected  sufficiently  to  make  them  com- 
mercially practical  and  usable,  namely  the  Buflovak  Rapid  Cir- 
culation Evaporator,  invented  and  manufactured  by  the  Buffalo 
Foundry  and  Machine  Co..  Buffalo,  N.  Y.,  and  the  Continuous 
Concentrator,  invented  by  the  By-Products  Recovery  Co.,  To- 
ledo, Ohio,  and  manufactured  by  the  Creamery  Package  Manu- 
facturing Co.,  Chicago. 

BUFLOVAK  RAPID  CIRCULATION  EVAPORATOR 

This  type  of 
Evaporator  has  been 
developed  from  the 
standard  return-flue 
tubular  boiler  and 
adopted  for  the  spe- 
cial purpose  of  hand- 
ling foamy  and  del- 
icate liquors. 

Construction.  — 
The  Buflovak  Rapid 
Circulation  Evapora- 
tor consists  of  a 
horizontal  cylindric- 
al vapor  body.  To 
this  is  bolted  an  in- 
c  1  i  n  e  d  cylindrical 
steam-chest. 

The  vapor  body 

is     ennirmed     with     a       F'9-  50-     Tne  Buflovak  rapid  circulation  evaporator 
equipped     Wit  Courtesy  of  Buffalo  Foundry   &  Machine  Co. 


CONTINUOUS  PROCESS  EVAPORATORS 


135 


baffle  plate  which  extends  across  its  cylindrical  part  and  leaves 
opening's  at  both  ends  of  the  vapor  body  for  the  vapors  to  escape, 
the  ends  or  heads  of  the  vapor  body  being  dished  outward.  The 
vapor  body  also  carries  the  milk  inlet,  vapor  outlet  and  spy 
glasses. 

The  steam  chest  which  is  attached  to  the  lower  part  of  the 
vapor  body,  is  divided  by  a  solid  partition  into  two  compart- 
ments. The  upper  and  larger  compartment  is  filled  with  tubes 
which  are  expanded  in  the  flue-sheets,  closing  both  ends.  The 
tubes  themselves  are  open  at  both  ends.  They  are  two  inches 
in  diameter  and  from  six  to  eight  feet  long.  The  lower  and  small 
compartment,  called  the  downtake,  is  entirely  open  at  both  ends. 
The  steam  chest  is  equipped  with  a  steam  inlet,  a  liquor  outlet 
and  a  condensation  outlet  or  drip.  The  steam  is  around  the  tubes 
and  the  milk  is  inside  the  tubes. 

Operation.-— This  machine  is  operated  under  vacuum  of  from 
26  to  28  inches  mercury  column,  the  vapor  outlet  being  connected 
with  a  condenser  and  vacuum  pump. 

.  The    fluid    milk 

enters  the  vapor 
body  and  flows  down 
into  the  bottom  of 
the  downtake  of  the 
steam  chest,  from 
where  it  rises  in  the 
tubes  and  finds  its 
level.  The  level  of 
the  milk  in  the  tubes 
"  is  kept  low,  the  co- 
efficient of  the  heat 
transmission  being 
highest  when  the 
milk  level  in  the 
tubes  is  about  one-third  of  the  tube  length  above  the  lower  flue- 
plate,  and  it  is  regulated  by  automatic  float  controls  in  the  larger 
machines.  The  steam  that  is  turned  into  the  steam  chest,  causes 
the  milk  in  the  tubes  to  boil.  The  vapor  thus  arising  from  the 
milk,  together  with  a  portion  of  the  milk  rises  and  passes  through 


5ECTIOH 


Fig.    51.     Cross    section    of    Buflovak 

rapid     circulation     evaporator 

Courtesy    of    Buffalo   Foundry   & 

Machine    Co. 


136  CONTINUOUS  PROCESS  EVAPORATORS 

the  upper  part  of  the  tubes  at  a  very  high  speed,  and  is  thrown 
with  great  force  against  the  ribs  of  the  baffle  plate  which  extends 
across  the  Avhole  cylindrical  length  of  the  vapor  body. 

The  liquid  or  condensed  milk  returns  through  the  down- 
take  to  the  lower  part  of  the  steam  chest  where  it  escapes  from 
the  machine.  The  vapor  passes  at  both  ends  of  the  baffle  plate 
into  the  vapor  space  above  and  from  there  through  the  entrain- 
ment  separator  for  reclaiming  escaping  milk,  and  then  to  the 
condenser  attached  to  the  outlet  of  the  vapor  body. 

The  upper  part  of  the  tubes  becomes  covered  with  a  climbing 
film  of  milk.  This  together  with  the  high  speed  of  the  milk  in  the 
tubes  (100  feet  per  second  or  more)  increases  the  capacity  of  the 
heating  surface,  and  the  small  amount  of  milk  in  circulation, 
together  with  the  low  level  of  the  milk  in  the  tubes,  reduces  the 
possibility  of  foaming,  confining  the  foam  to  and  breaking  it  up 
in  the  upper  part  of  the  tubes  where  film  evaporation  takes  place. 

The  escape  of  the  condensed  milk  is  continuous  and  the 
degree  of  concentration  is  controlled  by  a  valve  regulating  the 
outlet.  The  condensed  milk  runs  by  gravity  from  the  steam 
chest  into  a  reservoir  located  under  the  evaporator.  In  this  case 
the  reservoir  must  be  under  the  same  vacuum  as  the  evaporator. 
In  some  cases  it  is  recommended  to  have  an  intermediate  storage 
tank  removing  the  condensed  milk  from  the  evaporator  by  a  spe- 
cially constructed  steam  pump. 

THE  CONTINUOUS  CONCENTRATOR 

The  inflow  of  the  fluid  milk  and  the  outflow  of  the  condensed 
milk  are  continuous.  The  milk  is  condensed  under  atmospheric 
pressure  at  212°  F.  A  rapidly  revolving  agitator  throws  the  milk 
in  a  thin  film  against  the  steam-heated  and  continuously  polished 
periphery  of  a  jacketed  copper  drum.  By  keeping  the  heating 
surface  clean  and  bright,  and  the  milk  rapidly  moving,  the  power 
of  the  milk  to  absorb  and  utilize  heat  is  greatly  augmented  and 
the  rapidity  of  evaporation  increased. 


CONTINUOUS  PROCESS  EVAPORATORS 


137 


Description  of  Continuous  Concentrator. — The  continuous 
concentrator  consists  of  a  hollow  copper  drum.  The  copper  shell 
is  surrounded  by  a  steam  jacket  which  is  insulated.  The  space 
between  inner  shell  and  jacket  is  about  one  inch. 

This  drum  carries 
in  its  interior,  a  re- 
volving dasher  with 
four  or  more  blades, 
according  to  the  size 
of  the  machine,  and 
similar  to  an  ice  cream 
freezer  or  a  flash  pas- 
teurizer. The  edge  of 
these  blades  comes  in 
direct  contact  with  the 
inner  surface  of  the 
shell  which  is  the  heat- 
ing surface,  so  that 
when  revolving,  each 
blade  constantly  re- 
moves from  the  heating 
surface  any  milk  that 
adheres  to  it. 

The  blades  are  pres- 
sed against  the  heating 
surface  by  the  centri- 
fugal force  that  is 

generated  when  the  machine  is  in  motion.  The  arms  to  which 
the  blades  are  attached  are  equipped  with  stops  that  control 
their  pressure  against  the  heating  surface  so  as  to  insure  con- 
tinuous and  uniform  pressure.  The  shaft  which  carries  the 
dasher  passes  through  the  front  and  rear  heads  of  the  concen- 
trator and  carries  a  pulley  back  of  the  rear  head,  to  which  the 
power  is  transmitted. 

The  rear  of  the  concentrator  terminates  in  the  exhaust 
chamber  of  the  condensed  milk  vapors,  which  escape  through  a 
galvanized  iron  flue  to  the  outside.  The  vapors  are  not  condensed 
by  water,  but  escape  into  the  atmosphere.  The  rear  wall  is 
equipped  with  the  intake  of  the  fluid  milk.  In  order  to  permit 


Fig.  52.     The  continuous  concentrator 
Courtesy  of  The  Creamery   Package  Mfg.   Co. 


138  CONTINUOUS  PROCESS  EVAPORATORS 

the  milk  to  feed  the  concentrator  by  gravity,  without  necessitat- 
ing inconveniently  high  elevation  of  the  forewarmer,  the  intake 
is  located  at  the  bottom. 

In  the  front  head,  in  close  proximity  to  the  periphery  of  the 
concentrator  is  located  the  outlet  of  the  condensed  milk.  Its 
distance  from  the  inside  wall  of  the  concentrator  determines  the 
thickness  of  the  film  of  condensed  milk  that  is  allowed  to  form 
on  the  heating  surface,  and  the  amount  of  milk  that  is  retained 
in  the  concentrator.  According  to  the  amount  of  superheating 
intended,  this  film  may  vary  from  J  to  ^  inch  in  thickness  and 
the  amount  of  milk  retained  in  the  machine  may  vary  from  6 
to  12  quarts. 

The  front  head  is  equipped  with  a  cover  which  is  fastened 
to  the  rim  with  screw  bolts  and  which  carries  a  spy  glass  through 
which  the  operator  may  watch  the  process.  At  the  conclusion 
of  the  operation  this  cover  is  removed  and  the  dasher  and  blades 
are  taken  out,  so  that  both  the  shell  and  the  dasher  can  be  readily 
washed.  Over  the  top  of  the  concentrator  extends  the  steam 
line,  a  3  inch  pipe,  with  H  inch  laterals,  supplying  the  steam 
jacket,  and  insuring  uniform  distribution  of  heat.  The  steam 
line  is  also  equipped  with  regulator  and  steam  gauge.  At  the 
bottom  of  the  concentrator  is  located  the  exhaust  and  regulating 
drip  valve. 

The  continuous  concentrator  is  constructed  of  diverse  sizes 
and  capacities,  the  most  common  of  these  sizes  are  the  following: 

Capacity  when     Boiler  Capacity 

Diameter  Length          Concentrating  required 

at  the  ratio  H.  P. 


of  3:1 

3  feet 

4  feet 

4000  Ibs. 

100  H.  P. 

3  feet 

3  feet 

3000  Ibs. 

80  H.  P. 

3  feet 

2  feet 

2000  Ibs. 

40  H.  P. 

Speed  of  Agitator. — The  proper  speed  of  the  continuous 
concentrator  is  expressed  in  terms  of  rim  speed,  that  is  the 
distance  which  the  blades  travel  per  minute.  It  has  been 
found  that  the  rim  speed  which  is  sufficient  to  move  the  film 


CONTINUOUS  PROCESS  EVAPORATORS  139 

of  milk  in  the  machine  properly,  is  about  2500  feet  per  minute. 
In  order  to  insure  a  rim  speed  of  2500  feet  per  minute,  the  blades 

2500 

in  a  3  feet  diameter  machine  must  revolve  •.    .  t  .    =  265  times 

3x3.14 

per  minute.     In  a  six  foot  diameter  wheel,  the  same  rim  speed 

2500 
would  require  •     7  -.  /  =133  revolutions  per  minute  of  the  spider. 

OXO.l'T 

Again  it  has  been  found  that  the  blades  should  be  not  more 
than  about  2\  feet  apart.  A  three  foot  diameter  concentrator, 
therefore,  requires  four  blades  while  concentrators  with  larger 
diameter  require  a  larger  number  of  blades  in  order  to  keep  the 
distance  between  blades  within  the  limit  of  two  and  one-half 
feet. 

Operation  of  Continuous  Concentrator. — The  operation  of 
the  continuous  concentrator  is  simple  and  the  ratio  of  concentra- 
tion of  the  product  can  be  regulated  as  desired. 

Heating  of  Milk. — Similar  as  in  case  of  evaporation  in  vacuo, 
it  is  desirable,  if  not  necessary,  to  heat  the  milk  before  it  enters 
the  concentrator.  This  not  only  increases  the  capacity  of  the 
machine,  but  it  also  prepares  the  casein  in  the  milk  for  the 
superheating  to  which  the  milk  is  subjected  in  the  concentrator. 
Any  method  of  forewarming  or  preheating  may  be  used  for  this 
purpose,  but  since  the  milk  flows  to  and  through  the  concen- 
trator, in  a  continuous  stream,  it  is  preferable  to  also  use  a  fore- 
warmer  of  the  continuous  type.  The  milk  should  be  heated  to 
about  185  to  200°  F.  and  the  forewarming  should  be  so  arranged 
that  the  milk  is  exposed  to  this  temperature  for  5  to  10  minutes 
before  it  enters  the  concentrator. 

Condensing. — The  concentrator  is  steamed,  the  parts  of  the 
agitator  are  assembled  and  installed  in  their  proper  place,  the 
cover  is  securely  bolted  over  the  opening  in  the  front  head  and 
the  machine  is  ready  for  operation.  Before  starting  the  agitator 
a  small  amount  of  milk  is  permitted  to  flow  into  the  concentrator 
so  as  to  avoid  the  blades  from  running  over  the  dry  heating  sur- 
face, cutting  the  copper.  Simultaneously  with  the  starting  of  the 


140  CONTINUOUS  PROCESS  EVAPORATORS 

agitator  the  steam  is  turned  into  the  jacket  and  then  the  milk 
intake  valve  is  opened. 

The  steam  pressure  on  the  jacket  is  kept  uniform,  preferably 
at  40  to  50  Ibs.  of  steam.  This  machine  evaporates  the  milk  at 
atmospheric  pressure.  The  temperature  of  the  milk  in  the  con- 
centrator therefore,  is  practically  the  same  as  that  of  boiling 
water — 212°  F. — at  the  sea  level  and  varies  only  with  the 
altitude  of  the  location.  The  ratio  of  concentration  is  regulated 
by  the  rate  of  the  milk  inflow.  As  the  milk  inflow  is  increased, 
the  ratio  of  concentration  is  reduced,  because  the  amount  of 
evaporation  being  constant,  a  smaller  proportion  of  the  water  is 
taken  out  of  the  milk. 

The  density  is  determined  by  the  use  of  the  Beaume  hydro- 
meter. If  the  density  is  greater  than  desired,  more  milk  is 
allowed  to  flow  into  the  machine.  If  the  density  is  lower  than 
desired  the  inflow  of  milk  is  reduced. 

Cooling  of  Condensed  Milk. — From  the  discharge  spout  the 
condensed  milk  is  run  over  a  continuous  cooler  from  which  it 
escapes  ready  for  packing  in  whatever  form  it  is  intended  for. 
The  disc  continuous  cooler  has  proven  very  suitable  for  this 
purpose. 

No  subsequent  superheating  of  the  concentrated  milk  is 
necessary.  This  product  can  be  made  of  any  consistency  desired, 
regardless  of  concentration,  according  to  the  thickness  of  the 
film  that  is  allowed  to  form  in  the  concentrator,  and  this  in  turn 
depends  on  the  distance  of  the  discharge  from  the  periphery  of 
the  machine. 

Type  of  Products  that  can  be  made  by  the  Use  of  the  Con- 
tinuous Concentrator. — The  continuous  concentrator  can  be  used 
for  the  manufacture  .of  all  types  of  unsweetened  condensed  milk, 
such  as  plain  condensed  bulk  milk,  evaporated  milk,  condensed 
buttermilk,  condensed  whey. 

For  sweetened  condensed  milk,  it  would  be  necessary  to 
delay  the  addition  of  the  sugar  until  after  condensing,  in  which 
case  the  sugar  would  have  to  be  added  in  the  form  of  a  syrup. 
This  phase  has  not  as  yet  been  worked  out  on  a  practical  scale, 
and  demands  further  investigation  before  definite  directions  can 
be  given. 


CONDENSED  BUTTERMILK  141 

When  properly  operated,  the  continuous  concentrator  yields 
a  product  of  excellent  flavor  and  good  quality.  Contrary  to 
popular  assumption,  that  milk  exposed  to  so  hot  a  heating  surface 
(40  to  50  Ibs.  steam  pressure  which  equals  a  temperature  of 
about  260°  F.  to  280°.  F.,  develops  a  pronounced  cooked  flavor, 
this  product  is  remarkably  free  from  this  off-flavor,  its  solubility 
is-  not  materially  affected,  and  its  body  is  smooth. 

CHAPTER  XV. 
CONDENSED  BUTTERMILK 

The  value  of  buttermilk  as  a  chicken  feed  is  rapidly  gaining 
recognition.  Buttermilk,  similar  to  skim  milk  and  whole  milk, 
is  a  highly  satisfactory  feed  for  fattening  chickens.  Its  value 
is  enhanced  by  the  superior  quality  of  the  meat  from  buttermilk- 
fed  chickens  and  by  increased  egg  production  of  laying  hens. 
For  similar  reasons  buttermilk  which  is  the  foundation  of  a  good 
hog,  is  becoming  a  more  and  more  indispensable  part  of  the  ration 
fed  to  pigs  and  hogs. 

Since  the  great  bulk  of  butter  is  manufactured  during  the 
summer  season  the  main  supply  of  buttermilk  is  confined  to  the 
summer  months.  In  summer  the  output  of  buttermilk  far  exceeds 
the  demand  for  this  product  and  much  of  it  goes  to  waste  for 
lack  of  a  suitable  market  for  it.  In  winter,  on  the  other  hand, 
the  output  of  buttermilk  is  small  and  insufficient  to  supply  the 
demand. 

In  order  to  stop  this  waste  of  buttermilk  in  summer,  to  utilize 
it  economically  and  profitably  and  to  equalize  the  supply 
throughout  the  year,  some  of  the  large  creameries  of  the  country 
have  found  it  practicable  and  profitable  to  condense  the  surplus 
buttermilk.  Information  from  chicken  feeders  and  hog  feeders 
shows  that,  when  re-diluted  to  the  consistency  of  the  original 
buttermilk,  this  condensed  buttermilk  gives  equally  as  satis- 
factory results  as  the  fresh  buttermilk. 

Manufacture. — There  are  many  methods  whereby  butter- 
milk can  be  and  is  being  reduced  in  .volume.  The  most  common 
ones  are:  Separation  of  whey  by  gravity,  evaporation  in  vacuo. 
evaporation  by  blowing  hot  air  through  it,  evaporation  by  the 
continuous  concentrator,  centrifugal  separation. 


142  CONDENSED   BUTTERMILK 

Separation  of  Whey  by  Gravity. — Much  of  the  so-called 
condensed  buttermilk  that  reaches  the  market  is  not  the  result 
of  evaporation  of  a  portion  of  the  water  contained  in  the  butter- 
milk, but  is  produced  by  permitting  the  curd  to  settle  by  gravity 
and  then  drawing  off  and  rejecting  the  whey. 

In  this  case  the  fluid  buttermilk  is  pumped  into  a  wooden 
tank,  either  a  horizontal  vat  or  a  vertical  stave  tank.  The  tank 
usually  contains  several  outlets  with  gates,  located  at  different 
heights,  to  facilitate  the  removal  of  the  whey.  The  tank  may 
or  may  not  be  equipped  with  steam  pipes  for  heating.  The  butter- 
milk is  heated  to  boiling  point  in  these  tanks  either  by  blowing 
live  steam  into  it,  or  by  running  steam  through  the  pipes  installed 
in  the  tank.  This  heat  is  maintained  for  several  hours.  This  causes 
the  casein  to  contract  and  settle  to  the  bottom  in  the  form  of 
fine  particles  of  curd,  leaving  on  top  a  clear  whey.  This  whey 
is  drawn  off  through  the  gates  located  above  the  stratum  of 
curd.  The  residue,  consisting  largely  of  casein,  water  and  some 
lactic  acid  and  milk  sugar,  represents  the  condensed  buttermilk. 
The  concentration,  or  more  correctly  speaking,  the  reduction  in 
volume  thus  effected,  is  at  the  ratio  of  about  4  to  5  parts  of  fluid 
buttermilk  to  one  part  of  condensed  buttermilk.  It  is  obvious  that 
in  this  form  of  concentration  all  of  the  valuable  food  elements  of 
the  buttermilk  are  not  reclaimed.  Most  of  the  milk  sugar  and 
much  of  the  lactic  acid  escape  in  the  whey  and  are  lost.  However, 
the  equipment  required  for  this  process  is  very  simple  and  in- 
expensive and  the  process  requires  no  special  knowledge  on  the 
part  of  the  creamery  personnel. 

Evaporation  in  Vacuo. —  This  is  accomplished  in  a  similar 
manner  as  is  the  case  in  the  manufacture  of  sweetened  condensed 
milk.  The  buttermilk  is  condensed  in  the  vacuum  pan.  Earlier 
trials  of  this  method  did  not  prove  entirely  satisfactory,  especial- 
ly because  of  the  tendency  of  the  curd  in  the  buttermilk  to  stick 
to  the  coils  and  the  sides  of  the  pan.  Another  objection  was  the 
relatively  high  initial  cost  of  equipment — the  vacuum  pan  and 
pump. 

In  order  to  avoid  the  sticking  of  the  curd,  attempts  have  been 

made  to  neutralize  the  buttermilk  before  evaporation  by  the  ad- 

'  dition  to  it  of  such  alkalies  and  alkaline  earths  as  sodium  carbon- 


CONDENSED  BUTTERMILK  143 

ate,  sodium  bi-carbonate,  milk  of  lime,  ammonium  hydrate,  and 
ammonium  carbonate. 

Since  one  of  the  virtues,  for  which  buttermilk  is  of  special 
value  for  feeding  purposes,  is  its  relatively  high  content  of  lactic 
acid,  it  is  obvious  that  by  neutralization  the  manufacturer  is 
robbing  the  condensed  buttermilk  of  the  very  ingredient  thai 
renders  it  most  wholesome  and  dietetically  valuable. 

Furthermore,  while,  with  the  exception  of  milk  of  lime,  these 
alkalies  add  nothing  to  the  product  that  is  of  acknowledged  bene- 
fit as  a  food,  the  addition  of  caustic  alkalies  in  quantities  suffi- 
cient to  reduce  the  precipitation  of  the  curd  and  to  prevent  its 
sticking  on  to  the  pan,  is  detrimental  to  the  wholesomeness  of 
the  finished  product. 

There  are  now  several  firms  in  this  country  who  claim  to 
have  perfected  a  method  of  condensing  buttermilk  in  vacuo,  that 
eliminates  most  of  the  difficulties  formerly  encountered  and  the 
expensive  copper  pan  is  being  replaced  for  this  purpose  by  one 
of  cheaper  material. 

Evaporation  by  Blowing  Hot  Air  through  the  Buttermilk. — 

This  refers  to  the  Campbell  process  of  making  concentrated  milk 
as  described  on  page  132.  This  method  has  not  come  into  general 
use  and  its  practicability  for  concentrating  buttermilk  is  as  yet 
untried. 

Evaporation  by  the  "Continuous  Concentrator."— There  is 

every  reason  to  believe  that  the  use  of  the  "Continuous  Concen- 
trator" for  condensing  buttermilk  is  a  commercially  practical 
proposition.  Experiments  have  demonstrated  that  a  condensed 
buttermilk  of  very  good  quality  can  be  made  by  this  process  and 
a  very  high  degree  of  concentration  can  be  accomplished.  It  is 
probable  that  the  future  will  see  many  of  these  machines  installed 
in  creameries  for  the  purpose  of  condensing  buttermilk.  See  also 
"Condensing  Milk  by  the  Continuous  Process,"  pages  133-141. 
Concentration  by  Centrifugal  Separation. — For  many  years, 
efforts  have  been  made  to  remove  the  water  from  the  buttermilk 
by  centrifugal  separation.  Machines  are  now  on  the  market  and 
in  use,  in  which  the  curd  of  the  buttermilk  collects  on  the  walls 
of  a  revolving  basket  while  the  whey  is  centrifuged  out.  These 
machines  are  similar  in  principal  to  the  well-known  laundry 
centrifuge.  They  have  been  successfully  used  by  creameries  that 


144  CONDENSED  BUTTERMILK 

are  engaged  in  the  manufacture  of  buttermilk  cheese.  Their 
operation,  however,  is  intermittent  only.  When  the  basket  fills 
up  with  the  curd,  the  machine  must  be  stopped  and  the  curd 
removed. 

For  the  purpose  of  handling  large  volumes  of  buttermilk 
daily  these  centrifuges  are  obviously  not  well  adapted.  They 
are  too  limited  in  capacity  and  in  speed  and  in  volume  of  perform- 
ance. Efforts  to  devise  a  centrifuge  for  continuous  operation, 
similar  to  the  cream  separator,  have  so  far  failed.  The  specific 
gravity  of  the  curd  in  the  buttermilk  is  so  nearly  like  that  of  the 
whey,  that  the  centrifugal  separator  refuses  to  discharge  a  liquid 
rich  in  curd  and  one  of  practically  clear  whey.  Experiments  by 
the  author  have  demonstrated  that,  no  matter  how  the  outlets  of 
the  discharges  are  adjusted,  both  liquids  have  practically  the 
same  composition. 

Packing  Condensed  Buttermilk. — Condensed  buttermilk  is 
usually  filled  in  wooden  barrels,  similar  to  glucose  barrels.  On 
account  of  its  high  lactic  acid  content  it  keeps  without  spoiling 
for  a  considerable  length  of  time.  For  prolonged  storage,  it 
should  be  held  in  the  cold.  Its  keeping  quality  naturally  depends 
largely  on  the  method  of  condensation,  the  degree  of  concentra- 
tion and  the  amount  of  acid  present.  Condensed  milk  produced 
by  evaporation  of  a  portion  of  its  water  contains  more  lactic  acid 
than  that  which  is  the  result  of  gravity  separation.  Evaporated 
condensed  buttermilk  may  keep  for  months  at  ordinary  tempera- 
ture. Wheyed-off  condensed  buttermilk  will  spoil  in  a  few 
weeks,  if  held  at  ordinary  temperatures. 

Chemical  Composition  of  Condensed  Buttermilk. — The  com- 
position of  condensed  buttermilk  naturally  varies  with  the  compo- 
sition of  the  original  buttermilk  and  the  nature  and  the  degree 
of  concentration.  Since  these  three  factors  are  not  constant,  the 
composition  of  the  finished  product  may  vary  within  compara- 
tively wide  limits. 

The  following  analyses  show  the  composition  of  two  samples 
of  buttermilk  condensed  in  a  vacuum  pan. 


CONDENSED  WHEY  145 

Composition  of  Condensed  Buttermilk 

Not  Partly  neutralized  by 

neutralized  ammonium  hydroxide 

Total  solids                                   51.48  40.90 

Moisture                                         48.52  59.10 

Ash                                                  3.93  3.70 

Curd                                               18.93  15.38 

Lactose                                          26.30       .  15.76 

Lactic  acid                                        3.60  2.52 

Ammonium  hydroxide                     .00  .88 


Total  101.28  97.34 

Uses  of  Condensed  Buttermilk. — Most  of  the  condensed  but- 
termilk is  sold  to  chicken  feeders.  It  brings  from  about  four  to 
six  cents  per  pound. 

Condensed  buttermilk  has  also  found  a  limited  demand  as 
human  food.  It  is  claimed  to  be  a  most  wholesome,  readily 
digestible,  nutritious  and  palatable  food.  Its  wholesomeness  and 
digestibility  are  attributed  to  its  high  lactic  acid  content.  It  is 
best  put  on  the  market  in  glass  bottles.  Its  keeping  quality  is 
enhanced  by  the  high  per  cent  of  lactic  acid  it  contains. 

CONDENSED  WHEY,  MYSEOST,  OR  PRIMOST 

The  condensing  of  whey  is  a  practice  which  originated  in 
vScandinavia.  The  original  process  consisted  of  straining  the 
whey  into  a  kettle  or  large  open  pan  over  a  fire.  "The  albuminous 
material  that  precipitates  and  rises  to  the  surface  is  skimmed 
off."1  The  whey  is  evaporated  as  rapidly  as  possible  with  con- 
stant and  thorough  stirring.  When  it  has  reached  about  one- 
fourth  of  its  original  volume  the  albumin  previously  skimmed 
off  is  returned  and  stirred  thoroughly  to  break  up  all  possible 
lumps.  When  the  whey  has  attained  the  consistency  of  thick- 
ened milk  it  is  poured  quickly  into  a  wooden  trough  and  stirred 
with  a  paddle  until  cool,  to  prevent  the  formation  of  large. sugar 
crystals.  It  can  then  be  molded  into  the  desired  form  for  market. 


1  United  States  Department  of  Agriculture,  Bureau  of  Animal  Industry,  Bul- 
letin  No.    105. 


146  CONDENSED  WHEY 

A  more  rapid  method  of  making  primost  is  to  evaporate  the 
whey  in  the  vacuum  pan.  When  the  syrup  has  reached  the 
desired  density  it  is  drawn  off,  allowed  to  cool  and  pressed  into 
bricks.  The  product  has  a  yellowish-brown  color,  gritty  texture 
and  sweetish  taste.  The  evaporation  of  whey  in  vacuo  is  as  yet 
a  rare  practice  and  the  demand  for  the  finished  product  is  very 
limited. 

Experiments  with  the  " Continuous  Concentrator"  have 
demonstrated  that  condensed  whey  of  good  quality  can  readily 
be  prepared  with  this  machine.  The  concentration  can  be  carried 
as  far  as  15  to  1 ;  whey  so  condensed  escapes  from  the  concen- 
trator still  in  liquid  form,  but  changes  to  a  solid  upon  cooling, 
the  milk  sugar  in  this  supersaturated  solution  crystallizing  com- 
pletely. If  made  of  sour  whey,  the  product  thus  obtained  has  a 
splendid  clean  and  sharp  acid  flavor.  This  product  promises  to 
have  excellent  dietetic  properties,  and  also  to  lend  itself  admirably 
for  cooking  purposes. 


PART  IV. 
FROM  FACTORY  TO  CONSUMER 

CHAPTER  XVI. 
STAMPING 

Every  well  regulated  condensing  factory,  selling  condensed 
milk  in  hermetically  sealed  tin  cans,  employs  some  system  of 
marking  the  cans.  This  is  important  for  future  reference. 

When  defective  condensed  milk  is  returned  to  the  factory, 
the  marks  on  the  cans  tell  the  manufacturer  the  date  of  manu- 
facture, and  his  own  record  on  file  in  the  factory  shows  the  con- 
ditions under  which  the  defective  milk  was  made.  In  this  way 
defects  can  usually  be  traced  to  their  causes  and  the  recurrence 
of  similar  trouble  can  be  avoided. 

In  some  factories  the  batches  of  condensed  milk  are  num- 
bered from  one  up,  and  the  cans  are  stamped  with  the  respective 
batch  number.  This  method  is  simple  but  may  prove  undesirable, 
since  it  informs  the  competitors  also  of  the  date  of  manufacture 
of  competing  brands.  In  most  factories  a  code  of  letters  and 
figures  is  used,  designating  the  factory,  the  date,  and  the  number 
of  the  batch  of  each  day.  Thus  for  instance :  a  concern  has  three 
factories,  A,  B  and  C.  X  stands  for  the  current  year,  the  letters 
E,  F,  G,  H,  I,  J,  K,  L,  M,  N,  O,  P  indicate  the  twelve  months 
of  the  year,  respectively,  the  figures  1,  2,  3,  4,  etc.,  represent  the 
day  of  the  month  and  also  the  batches  of  condensed  milk  made 
in  one  day. 

Example :  A  can  of  condensed  milk  belongs  to  the  second 
batch  made  April  9,  1918,  at  factory  B.  The  can  would  be 
stamped  as  follows :  B  9  H  X  2. 

The  cans  are  usually  stamped  on  the  bottom,  that  is,  on  the 
end  which  carries  the  cap.  The  stamping  is  done  by  the  sealer. 
Small  interchangeable  rubber  letters  and  figures  are  used.  The 
stamping  ink  should  contain  a  drier  and  be  waterproof.  In  small 
factories  the  stamping  is  done  by  hand.  It  can  be  done  very 


148  INSPECTION  OF  CANS 

rapidly.  In  large  factories  an  automatic  stamping-  outfit  is  at- 
tached to  the  filling,  sealing  or  labeling  machine  and  the  cans 
are  stamped  automatically  while  they  are  being  filled,  sealed, 
or  labeled. 

INSPECTING 

The  sealed  and  stamped  cans  are  placed,  with  caps  down,  in 
wooden  trays  holding  twenty-four  medium-sized  cans.  All  trays 
of  one  batch  are  stacked  together.  A  card  indicating  number 
and  date  of  batch  and  number  of  cans  in  the  batch  is  attached 
to  the  stack  and  a  copy  of  the  same  is  filed  in  the  office.  The  cans 
are  placed  with  their  caps  down  in  order  to  detect  " leakers" 
(cans  with  defective  seals).  Before  labeling,  the  trays  should 
be  taken  down,  the  cans  turned  over  and  examined  for  leaky 
seals.  Unless  the  factory  is  behind  in  filling  orders  the  cans  will 
have  been  in  stock  at  least  twenty-four  hours  or  usually  longer. 
In  the  case  of  sweeetened  condensed  milk,  if  any  seals  are  de- 
fective, a  little  condensed  milk  will  have  oozed  out  by  that  time. 
Inexperienced  sealers  are  prone  to  cause  a  high  percentage  of 
leaky  cans.  A  careful  sealer  may  reduce  the  number  of  leakers 
to  .1  per  cent. 

•  Checking  the  Work  of  the  Sealers. — In  order  to  regulate  and 
improve  the  Avork  of  the  sealers  and  to  locate  those  doing  poor 
work,  it  is  advisable  to  number  the  sealers  and  supply  each  with 
small  tin  tag's  bearing  his  or  her  respective  number.  Each  sealer 
drops  one  tag  into  each  tray  of  cans  sealed  by  him.  The  inspectors 
record  the  number  of  leakers  found  in  each  tray.  Thus  each 
sealer  is  charged  up  with  the  leakers  he  made. 

Disposition  of  Leaky  Cans. — Small  leaks,  in  the  case  of 
sweetened  condensed  milk,  can  usually  be  soldered  over  success- 
fully and  the  mended  cans  are  returned  to  their  respective 
batches.  In  the  case  of  very  defective  seals,  attempts  at  mending 
generally  cause  the  milk  in  the  can  to  burn,  forming  a  brown 
crust  on  the  cap,  which  spoils  the  can  for  the  market.  The  con- 
tents have  a  burnt  taste  and  smell,  and  upon  stirring,  brown  and 
black  specks  of  burnt  milk  appear.  It  is  best  to  cut  bad  leakers 
open  and  pour  the  contents  into  the  succeeding  batch  of  milk. 


LABELING  CANS  149 

Importance  of  Inspection. — The  above  description  of  inspec- 
tion refers  to  sweetened  condensed  milk.  This  work  is  neglected 
in  many  factories,  though  it  is  very  important.  It  may  save 
labels  and  boxes,  as  well  as  much  unnecessary  labor  in  unpacking 
cases  with  leaky  cans,  and  washing,  relabeling  and  repacking 
them  in  new,  clean  cases. 

In  the  case  of  evaporated  milk  (unsweetened,  sterilized)  all 
cans  coming  from  the  incubating  room  should  be  individually 
shaken  by  hand.  All  cans  showing  no  signs  of  bulging,  and  the 
contents  of  which  shake  with  the  characteristic  sound  and  be- 
havior of  a  liquid,  pass  inspection.  If  the  ends  of  the  cans  are 
bulging  or  the  contents  do  not  respond  to  the  shaking  with  the 
characteristic  sound  of  normal  milk,  they  are  rejected,  as  the 
evaporated  milk  in  them  has  either  undergone  gaseous  or  curd- 
ling fermentation,  and  is  spoiled. 

LABELING 

Labeling  Machines. — In  the  early  days  of  the  milk  condens- 
ing industry,  the  labeling  of  the  cans  was  done  by  hand,  involving 
much  time  and  considerable  expense.  Today,  especially  con- 
structed labeling  machines  are  almost  exclusively  used  for  this 
purpose.  The  efficiency  of  these  machines  is  such,  that  they 
have  become  a  permanent  fixture  in  practically  every  condensery 
selling  canned  goods.  They  are  adjustable  to  various  sizes  of 
cans  and  can  be  operated  by  hand,  motor,  or  belt  power. 

Principle  of  Labeling  Machines. — The  cans  are  placed  into 
a  chute  from  which  they  roll  into  the  machine  by  gravity.  They 
are  caught  by  two  endless  belts  which  draw  them  through  the 
machine.  They  first  pass  over  the  paste  box,  which  contains  an 
automatically  revolving  \vheel  covered  with  a  thick  layer  of  felt. 
The  felt  is  saturated  with  paste  or  glue  from  the  paste  box.  Each 
can  comes  in  contact  with  the  paste  wheel  and  receives  a  touch 
of  paste.  Then  the  cans  pass  over  the  label  box  containing  a 
stack  of  labels,  face  down.  Each  can  picks  up  one  label  which 
is  automatically  wrapped  around  the  can  as  it  runs  through  the 
machine.  The  label  box  is  equipped  with  an  automatic  feeder 
which  pushes  the  labels  up  as  fast  as  they  are  being  used.  The 


150  PACKING  IN  CASES 

labeled  cans  leave  the  machine  over  a  chute  which  slants  from  it. 
As  they  are  removed  they  are  packed  directly  into  cases. 

Wrinkles  and  Rust  Spots  on  Labels. — The  attractiveness 
of  the  package  depends,  largely,  on  the  neatness  of  the  label.  The 
use  of  too  thin,  too  thick,  or  too  much  paste  causes  the  labels  to 
wrinkle  on  the  cans.  The  paste  should  have  the  consistency  of 
heavy  dough  and  the  paste  wheel  should  be  so  adjusted  that  it 
barely  touches  the  passing  cans. 

Frequently  the  labels  of  the  cans  show  stains  and  spots.  This 
is  especially  true  in  the  case  of  old  goods,  and  is  due  either  to  a 
poor  quality  of  paper,  the  use  of  sour  paste  or  the  storing  of  the 
labeled  goods  in  damp  places.  Sour  paste  corrodes  the  cans  and 
causes  them  to  rust.  The  rust  penetrates  the  label  and  spoils 
the  appearance  of  the  package.  Trouble  of  this  kind  can  be 
avoided  by  preparing  fresh  paste  every  day.  Paste  saved  from 
the  previous  day  is  prone  to  sour  and  should  not  be  used.  The 
storing  of  the  labeled  goods  in  damp  places  also  often  causes 
rust  spots  as  well  as  moulds  on  the  labels.  Thin  and  soft  paper 
labels  more  easily  than  thick,  stiff  and  glossy  paper.  In  the 
latest  types  of  labeling  machines  the  use  of  ordinary  paste  has 
been  largely  superseded  by  that  of  specially  prepared  glue,  which 
removes  most  of  the  objectionable  features  of  the  ordinary  paste, 
does  not  damage  the  label  apd  makes  a  neater  package. 

PACKING 

The  labeled  cans  are  packed  in  cases  holding  from  six  to 
ninety-six  cans,  according  to  the  size  of  the  cans.  (One  case 
holds  six  1-gallon  cans;  forty-eight  14-,  15-,  16-,  and  20-ounce 
cans;  or  seventy-two  to  ninety-six  8-ounce  cans). 

The  sides,  bottom  and  top  of  the  cases  should  be  of  material 
about  three-eights  of  an  inch  to  one-half  inch  thick,  the  ends 
three-fourths  of  an  inch  to  seven-eights  of  an  inch  thick.  The 
cases  are  usually  bought  in  the  ''knock-down"  shape  and  are 
made  up  in  the  factory.  Sixpenny  cement-coated  wire  nails  are 
most  suitable  for  this  purpose.  The  cases  are  most  economically 
nailed  by  the  use  of  nailing  machines,  which  nail  one  entire  side 
or  one  side  and  one  end  simultaneously.  The  cans  are  usually 


PACKING  IN  CASES  151 

placed  into  the  cases  direct  from  the  labeling  machine.  In  some 
factories,  packing-  machines,  which  pack  twenty-four  medium- 
size  cans  in  one  operation,  are  used.  Formerly  condensed  milk 
cans  were  packed  exclusively  in  wooden  cases.  Within  the  last 
few  years  the  use  of  paste-board  and  fibre  boxes  has  been  adopted 
in  many  condenseries.  These  boxes  are  proving  very  serviceable 
for  domestic  trade,  and  prior  to  the  price  advance  on  paper  ma- 
terial caused  by  the  world  war,  they  made  possible  a  considerable 
saving  in  the  cost  of  the  package. 

Marking  the  Cases. — One  end  of  each  case  is  stenciled  with 
the  number  of  the  batch ;  over  the  other  end  is  pasted  a  case 
label,  representing,  enlarged,  the  brand  of  the  label  on  the  cans 
within.  In  the  place  of  the  case  label,  the  respective  brand  may 
be  printed  on  or  burnt  into  the  wood.  The  burnt  stencilling  is 
usually  done  by  the  manufacturer  of  the  shocks.  One  side  of 
each  case  is  usually  marked  "Condensed  Milk"  or  "Evaporated 
Milk,"  as  the  case  may  be;  the  other  "Keep  in  cool,  dry  place." 
[f  sweetened  condensed  milk  is  exposed  to  excessive  heat  for  a 
considerable  length  .of  time,  as  is  often  the  case  in  storehouses 
or  in  the  hold  of  steamers,  where  the  cases  may  be  stowed  against 
the  boiler  room,  it  becomes  brown,  thickens  rapidly  and  develops 
a  stale  flavor.  Evaporated  milk  also  darkens  when  exposed  to 
heat  and  depreciates  in  flavor.  It  should,  therefore,  be  kept  in 
a  cool  place.  The  humidity  of  the  storage  room  has  no  effect  on 
the  condensed  milk  proper,  the  cans  being  hermetically  sealed. 
Prolonged  exposure  to  dampness,  however,  will  moisten  the  paste 
under  the  labels.  This  causes  the  labels  to  wrinkle  and  the  paste 
to  become  sour  and  musty.  The  sour  paste  corrodes  the  cans 
and  rust  spots  penetrate  the  labels.  Such  cans  also  may  soon 
become  coated  with  mildew. 

Packing  Condensed  Milk  for  Export. — In  the  case  of  con- 
densed milk  bought  by  the  United  States  Government,  the.  cans 
are  dipped  in  a  solution  of  shellac  before  they  are  labeled,  or  the 
tin  plate  or  empty  cans  are  bought  by  the  manufacturer  already 
lacquered.  Cans  for  export  trade  and  in  many  instance  for  the 
home  market,  are  wrapped  into  heavy,  soft  paper,  bearing  on  the 
outside  a  copy  of  the  respective  brand.  This  wrapping  paper  takes 
up  the  space  between  the  cans  and  prevents  the  cans  from  being 
damaged  on  their  long  journey  and  by  rough  usage.  This  wrap- 


152  STORAGE; 

ping  is  usually  done  by  hand.  Some  makes  of  labeling  machines, 
however,  have  an  attachment  for  wrapping  the  cans  so  that  when 
the  cans  leave  the  machine  they  are  wrapped  as  well  as  labeled. 
The  cases  are  reinforced  with  a  band  of  strap  iron  around  each 
end.  Where  the  cases  have  to  be  loaded  and  unloaded  numerous 
times,  as  is  the  case  with  export  shipments,  they  are  in  danger  of 
being  torn  to  pieces,  unless  such  special  precautions  are  taken. 

CHAPTER  XVII. 
STORAGE 

Purpose  of  Storing. — The  purpose  of  storing  condensed  rnilk 
is  largely  the  same  as  that  of  storing  butter  and  other  produce, 
namely,  to  keep  the  product  from  the  time  of  large  supply  and 
low  prices,  to  the  time  of  small  supply  and  high  prices.  In  sum- 
mer time,  the  market  is  usually  flooded  with  condensed  milk 
throughout  the  country,  the  demand  for  it  is  at  ebb  tide  and  the 
prices  are  low.  In  winter,  there  is  usually  a  great  shortage  of 
condensed  milk,  the  demand  far  exceeds  the  supply  and  prices 
soar  high.  The  storing  of  summer  milk  may  be  necessary,  also, 
in  order  to  enable  the  manufacturer  to  fill  his  contracts  and  supply 
his  trade  in  winter.  This  is  especially  true  where  the  factories 
of  a  concern  are  located  in  new  territories  where  the  patrons 
produce  an  excessively  small  amount  of  winter  milk. 

Plain  condensed  milk  and  concentrated  milk  which  are  not 
sterile  and  contain  no  cane  sugar  to  preserve  them,  keep  but  a 
few  days  at  ordinary  temperatures  and  should,  therefore,  be  sold 
arid  used  as  soon  as  possible  after  manufacture.  If  their  storage 
is  unavoidable,  they  should  be  held  as  near  the  freezing  point  as 
possible.  For  prolonged  storage  it  might  be  advantageous  to 
freeze  them.  However,  reliable  data  on  this  phase  of  the  industry 
are  lacking. 

Evaporated  milk,  sold  in  hermetically  sealed  cans,  is  supposed 
to  be  entirey  sterile,  and,  if  made  properly,  will  keep  indefinitely, 
There  is  a  constant  tendency,  however,  for  the  fat  to  separate 
out,  which  naturally  is  augmented  by  prolonged  storage.  Again, 
the  lactic  acid  in  the  evaporated  milk  gradually  acts  on  the  can, 
causing  the  tinplate  to  become  dull  and  the  contents  to  aquire  a 
disagreeable  metallic  flavor.  When  stored  for  an  excessively  long 
time  this  chemical  action  may  be  sufficient  to  cause  the  evolution 
of  considerable  quantities  of  hydrogen  gas,  swelling  the  cans. 


STORAGE  153 

Sweetened  condensed  milk  which  is  preserved  by  about  40 
per  cent,  of  sucrose,  will  keep  apparently  unchanged  for  a  con- 
siderable length  of  time.  It  is  best,  however,  when  fresh.  Bac- 
teriological examinations  have  shown  that,  while  moderate  age 
does  not  change  the  outward  appearance  of  this  condensed  milk, 
the  bacteria  in  it  gradually  increase  and  the  milk  gradually  de- 
velops a  stale  flavor.  White  and  yellow  "buttons,"  lumps,  or 
nodules  of  a  cheesy  texture  and  flavor,  probably  due  to  some 
fungus  growth,  are  also  prone  to  appear  in  the  condensed  milk. 
Age,  also,  causes  it  to  become  darker  in  color.  These  defects  are 
especially  apparent  in  old  milk  which  has  not  been  kept  at  a 
low  temperature.  Again,  sweetened  condensed  milk  made  in 
May  and  June  has  a  strong  tendency  to  thicken  with  age  and  to 
become  entirely  solid. 

In  some  cases  a  part  of  the  sweetened  condensed  milk  made 
during  the  summer  months  is  stored  in  large  cylindrical  wooden 
or  iron  tanks  sunk  into  the  ground,  or  installed  in  the  basement 
of  the  factory,  where  the  condensed  milk  remains  at  an  even  tem- 
perature. As  the  demand  for  the  product  increases  and  the 
supply  of  fresh  milk  decreases,  condensed  milk  is  drawn  from 
these  tanks  to  fill  the  increasing  orders. 

Effect  of  Storage  Temperature. — Most,  if  not  all  the  changes 
which  condensed  milk  is  prone  to  undergo  in  storage  are 
retarded,  if  not  entirely  prevented,  when  stored  at  the  proper 
temperature.  Temperatures  of  60  degrees  F.  or  above  are  too 
high  for  satisfactory  storage  for  a  prolonged  period  of  time  and 
the  higher  the  temperature  the  greater  the  resulting  defect. 

Temperatures  below  the  freezing  point  of  water  are  also 
undesirable.  The  evaporated  milk  freezes  and  while  so  doing  it 
expands  sufficiently  to  swell  the  cans.  Although  this  swelling 
disappears  when  the  contents  of  the  cans  dissolve  again,  yet 
the  swelling  action  tends  to  weaken  the  cans  and  may  give  rise 
to  subsequent  leakers.  Again  the  melted  evaporated  milk  is 
prone  to  be  grainy  as  the  result  of  freezing.  This  is  due  to  the 
fact  that  when  freezing,  the  watery  portion  separates  from  the 
curd  and  the  latter  contracts.  When  the  milk  thaws  up  the  curd 
remains  contracted  and  fails  to  form  a  smooth  emulsion  with 
the  remainder  of  the  milk. 


154  STORAGE; 

The  sweetened  condensed  milk  does  not  freeze,  because  it 
contains  so  concentrated  a  sugar  solution  that  its  freezing  point  is 
usually  far  below  the  refriger- 
ating temperature.  If  it  is 
packed  in  solder-sealed  cans 
there  is  usually  no  bad  effect 
.from  cold  storage.  However, 
when  packed  in  cans  sealed 
with  the  friction  cap  or  the 
burr  cap,  difficulties  may  arise. 
These  seals  are  not  air-tight. 
Excessively  low  storage  tem- 
peratures cause  the  contents  to 
shrink  appreciably.  Suction  is 
formed  and  air  is  drawn  in 

through  the  seal.     When  these  F|g.  53.    The  stevenson  co|d  storage  door 
cans   again   warm   up,   the  vis-  Courtesy  of  stevenson  GO. 

cous  milk  in  the  cans  seals  the  microscopic  openings,  the  air  and 
the  liquid  expand  but  the  air  finds  no  exit.  This  causes  the  cans 
to  swell.  While  the  quality  of  the  milk  in  these  cans  is  not 
impaired  in  the  least,  the  swelled  cans  suggest  gaseous  fer- 
mentation, which  means  spoiled  milk  and  which  is  invariably 
rejected  on  the  market. 

The  temperatures  at  which  condensed  milk  can  be  stored 
with  least  objectionable  results,  range  between  32  and  50  de- 
grees F. 

Advisability  of  Storing. — A  heavy  stock  of  condensed  milk 
is  a  severe  drain  on  the  working  capital  of  the  condensery  in- 
volving the  cost  of  the  fresh  milk,  cane  sugar,  tinplate,  boxes, 
solder,  labels,  coal  and  labor. 

Unless  the  manufacturer  has  successfully  overcome  and  mas- 
tered all  of  the  principal  condensed  milk  defects,  and,  unless  his 
experience  justifies  him  in  believing  that  his  goods  will  stand 
the  trials  of  storage,  he  will  find  it  advisable  not  to  manufacture 
more  than  he  can  promptly  dispose  of.  Even  at  best,  the  con- 
densed milk  will  be  from  three  to  six  months  old  before  it  is  all 
consumed,  and,  if  it  is  at  all  subject  to  deterioration,  the  sooner 
it  is  consumed  the  better. 

But  even  if  the  condensed  milk  comes  out  of  storage  in  good 


MARKETS  155 

condition,  the  condition  of  the  market  may  be  such  that  the  goods 
cannot  be  sold  at  a  profit,  and  if  the  market  happens  to  take  a 
demoralizing  slump  at  the  time  the  goods  are  ready  to  leave  the 
storage,  the  manufacturer  may  suffer  heavy  loss.  This  condi- 
tion has  occurred  repeatedly  within  the  last  ten  yars. 

TRANSPORTATION 

The  plain  condensed  bulk  milk  and  concentrated  milk  are 
highly  perishable  products.  If  shipped  considerable  distances 
they  should  be  placed  in  refrigerator  cars. 

The  evaporated  milk  and  sweetened  condensed  milk  in  her- 
metically sealed  cans,  and  the  latter  also  in  barrels,  can  safely 
be  shipped  in  ordinary  box  cars.  The  cases  weigh  from  fifty 
to  sixty-five  pounds,  and  the  barrels  from  three  hundred  to  seven 
hundred  pounds.  Care  should  be  taken  that  the  cars  used  for 
this  purpose  are  clean  and  did  not  previously  carry  goods  with 
strong  and  obnoxious  odors,  such  as  fertilizers,  as  these  odors 
are  prone  to  follow  the  condensed  milk  to  its  destination.  Strong 
box  cars,  in  good  repair  only,  should  be  used.  Even  at  best, 
the  cases  and  cans  suffer  more  or  less  damage  in  transportation. 
Cars  with  leaky  roofs  should  be  condemned,  as  transportation  in 
them  may  cause  the  package  to  suffer  in  appearance.  If  shipped 
on  steamboats,  it  should  be  specified  to  stow  the  cases  away  from 
the  boiler  room,  as  prolonged  exppsure  to  high  temperatures 
causes  the  condensed  milk  to  deteriorate. 

CHAPTER  XVIII. 
MARKETS 

A  large  proportion  of  the  canned  condensed  milk,  both 
sweetened  and  unsweetened,  supplies  localities,  territories  and 
countries  where  the  dairy  industry  is  yet  in  its  infancy,  or 
where  geographic  and  climatic  conditions  bar  the  profitable 
husbandry  of  the  dairy  cow.  Thus,  we  find  some  of  the  best 
condensed  milk  markets  in  the  tropics,  in  the  arctic  regions,  in 
the  army  and  navy,  on  ocean  liners  and  in  mining  and  lumber 
camps.  In  these  markets  condensed  milk  has,  in  many  cases, 
become  as  great  a  necessity  as  fresh  milk  is  to  the  inhabitants 
within  the  temperature  zone.  The  consumption  of  canned  con- 


156  MARKETS 

densed  milk  in  our  home  markets  has,  also,  been  increasing 
rapidly  within  recent  years,  and  is  today  assuming  astonishing 
proportions.  The  rapid  growth  of  the  ice  cream  industry  has 
further  developed  a  splendid  and  ever-increasing  market  for 
plain  condensed  bulk  milk. 

It  is  estimated  that  the  canned  condensed  milk  is  from  three 
to  six  months  old  before  it  reaches  the  consumer.  It  is  usually 
sold  through  the  medium  of  a  jobber  or  broker  and  not  direct 
from  manufacturer  to  retailer.  In  its  transit  to  the  distant 
markets,  it  is  subjected  to  many  delays;  first,  by  its  storage  in 
the  factory,  then  the  time  in  transportation,  next,  the  delay  in 
the  warehouse  of  the  jobber,  broker  or  wholesale  dealer.  From 
there  it  gradually  finds  its  way  to  the  shelves  of  the  retailer, 
where  there  is  again  considerable  delay  before  it  reaches  the 
pantry  of  the  consumer. 

Market  Prices  of  Condensed  Milk. — The  price  of  condensed 
milk  is  not  controlled  by  the  general  market  of  dairy  products, 
nor  by  any  board  of  trade ;  there  is  no  consistent  uniformity  of 
price  throughout  the  country  as  is  the  case  of  butter  and  cheese. 
The  price  of  condensed  milk  does  not  necessarily  follow  the 
rise  and  fall  of  the  butter  and  cheese  markets,  but  in  the  long 
run  it  is  usually  affected  by  abrupt  fluctuations  of  prices  of  these 
other  dairy  products,  largely  on  account  of  the  influence  of  such 
fluctuations  on  the  supply  to  the  condensery  of  fresh  milk.  It 
is  chiefly  governed  by  local  conditions  of  supply  and  demand, 
composition  of  product  and  reputation  of  the  individual  brand. 
Condensed  milk  is  sold  under  hundreds  of  different  brands  or 
labels.  While  one  and  the  same  concern  may  sell  scores  of 
different  brands,  the  brand  itself  has  very  little,  if  anything,  to 
do  with  the  quality  or  composition  of  the  contents  of  the  can. 
Each  brand  usually  sells  at  its  own  special  price,  although  the 
various  brands  put  on  the  market  by  the  same  concern  often 
contain  the  same  quality  of  milk  and  may  be  filled  with  con- 
densed milk  from  one  and  the  same  batch.  It  is  customary  in 
most  factories  to  fill  the  cans  before  they  are  labeled  and  the 
orders  for  different  brands  of  condensed  milk  are  filled  from 
the  same  general  stock.  The  brands  serve  largely  as  an  in- 
strument to  increase  the  sales  and  "dodge"  competitors. 


MARKETS  157 

Sweetened  condensed  milk,  packed  in  hermetically  sealed 
cans,  sells  from  about  $3.25  to  $5  per  case  of  48  sixteen-ounce 
cans  and  the  cans  retail  at  from  5  to  20  cents  each,  according  to 
the  size  of  the  cans  and  market  conditions. 

Evaporated  milk,  unsweetened  condensed  milk  in  hermetic- 
ally sealed  cans,  sells  from  $2.25  to  $4.00  per  case,  according  to 
the  size  of  the  cans  and  market  conditions. 

Bulk  milk,  both  sweetened  and  unsweetened,  goes  direct 
from  the  manufacturer  to  the  purchaser  who  uses  it  at  prices 
agreed  upon  by  the  contracting  parties.  The  sweetened  con- 
densed milk  is  sold  in  barrels  holding  from  three  hundred  to 
seven  hundred  pounds  (usually  about  six  hundred  pounds)  to 
candy  and  caramel  factories,  bakeries  and  confectioners.  The 
price  varies  from  four  to  ten  cents  per  pound  according  to  the 
per  cent,  of  fat,  demand  und  supply.  When  there  is  a  general 
"epidemic"  of  bad  canned  condensed  milk,  as  is  often  the  case  in 
years  when  the  price  of  sugar  is  high,  due  to  failure  of  the  sugar 
cane  crop,  and  many  manufacturers  are  tempted  to  use  inferior 
cane  sugar,  which  they  buy  at  a  comparatively  low  cost,  this 
spoiled  condensed  milk  is  usually  turned  into  candy  shops  and 
bakeries,  where  it  is  sold  for  "a  song."  This  condition  has 
always  a  depressing  influence  on  the  price  of  sweetened  con- 
densed bulk  milk,  which,  during  such  seasons,  may  have  to  be 
sold  at  a  loss.  Some  milk  condensing  concerns  operate  their  own 
candy  shops  which  take  care  of  the  condensed  milk  that  is  re- 
jected on  the  market. 

Plain  or  unsweetened  condensed  milk  is  sold  in  1 -gallon  to 
10-gallon  cans  to  ice  cream  factories,  the  price  varying  from 
twenty-five  to  ninety  cents  per  gallon,  according  to  fat  content, 
concentration  and  market  conditions.  The  market  for  this  class 
of  goods  is  not  very  constant,  but  the  profits  are  generally  high. 
It  reaches  ebbtide  in  winter  when  the  demand  for  ice  cream  is 
small.  Limited  quantities  of  plain  condensed  bulk  milk  are  also 
sold  in  milk  and  cream  bottles  for  direct  consumption.  The 
concentrated  milk  finds  the  same  markets  as  the  plain  con- 
densed bulk  milk. 

The  above  range  of  prices  of  the  several  types  of  condensed 
milk  refers  to  the  market  conditions  which  prevailed  while  the 
industry  was  protected  against  competition  with  goods  from 


158  MARKETS 

abroad  by  an  import  tariff  of  2c  per  pound  or  $1.00  per  case  of 
condensed  milk,  and  to  conditions  prior  to  the  advent  of  the 
European  war  in  1914. 

In  1913,  the  United  States,  by  Act  of  Congress,  removed 
the  import  tariff,  placing  condensed  milk  on  the  free  list.  This 
Act  became  effective  in  the  fall  of  the  same  year.  Its  immediate 
effect  was  a  rapid  increase  in  the  importation  of  European  con- 
densed milk,  which  was  offered  for  sale  at  relatively  low  prices, 
decreased  the  sale  of  domestic  goods  and  caused  the  holdings  of 
condensed  milk  to  accumulate  in  large  quantities.  Condensed 
milk  prices  depreciated  rapidly  throughout  1914  and  reached 
the  bottom  in  the  fall  of  that  year  when  financial  limitations 
compelled  many  concerns  to  move  their  goods  at  any  price.  At 
that  time  the  bottom  prices  of  condensed  milk  were  approxim- 
ately as  follows : 

Sweetened  condensed  milk  per  case $2.50 

Evaporated  milk  per  case 1.90 

The  losses  suffered  by  this  slump  in  the  condensed  milk 
market,  caused  by  the  influx  of  cheap  foreign  goods  in  the 
absence  of  a  protective  tariff,  were  enormous  and  caused  bank- 
ruptcy of  numerous  of  the  financially  limited  concerns.  The 
outlook  for  the  future  of  the  industry  looked  very  uninviting 
at  best,  but  the  situation  was  saved  and  market  conditions 
reversed  by  the  urgent  food  requirements  of  the  Allied  nations 
in  the  European  war,  and  after  the  entrance  of  the  United  States 
into  the  World  War,  by  large  orders  for  the  American  army 
and  navy. 

The  extraordinary  and  very  urgent  demand  for  condensed 
milk  by  the  U.  S.  Government  and  by  its  allies  boosted  the 
prices  of  this  product  to  a  level  not  attained  since  the  Civil  war. 
The  profits  per  case  were  augmented  manyfold  of  those  of  normal 
periods  and  the  prices  paid  the  farmer  in  some  localities  rose 
to  as  high  as  $3.50  per  hundred  weight  and  75  cent  per  pound 
of  butterfat.  This  situation  naturally  made  it  easy  for  the  milk 
condensing  factories  to  encroach  on  the  milk  and  cream  supply 
territory  of  the  creameries  and  cheese  factories,  whose  products 
experienced  only  a  relatively  moderate  increase  in  price,  and 
not  at  all  proportionate  with  the  soaring  of  condensed  milk 
prices. 


MARKETS  159 

In  the  summer  of  1917,  the  Federal  Food  Administration,  in 
an  effort  to  control  the  prices  and  profits  of  condensed  milk, 
ruled  that  the  profits  on  condensed  milk  shall  not  exceed  30 
cents  per  case  on  an  average  for  the  year,  this  being-  considered 
the  average  pre-war  profit.  This  did  not  mean  that  the  govern- 
ment guaranteed  a  profit  of  30  cents  per  case,  it  merely  meant 
that  30  cents  per  case  was  the  maximum  profit  the  condenseries 
were  allowed  to  make.  This  ruling  applied  only  to  condensed 
milk  sold  to  the  government,  it  did  not  refer  to  the  goods  sold 
to  the  domestic  trade  nor  to  export  contracts.  The  national 
committee  of  condensed  milk  men  who  met  with  the  Federal 
Food  Administration  Committee,  however,  agreed  to  apply  the 
same  ruling  to  their  product  sold  to  the  domestic  trade. 

Profits  on  condensed  milk  supplied  to  the  allied  nations, 
however,  were  in  excess  of  this  figure,  partly  because  of  high 
prices  payed  for  this  export  milk  and  partly  because  of  the 
greatly  reduced  cost  of  selling  and  distributing. 

The  following  figures  show  wholesale  condensed  milk  prices 
in  1916  and  1917: 

January  June 

1916  1917 

per  case,  per  case. 

Sweetened  condensed  milk,  per  case $6.50  $8.75 

Evaporated  milk,  per  case 3.85  5.75 

Early  in  1918,  this  condensed  milk  boom  suffered  an  abrupt 
check  from  the  fact  that  the  transatlantic  bottoms  available 
proved  entirely  inadequate  to  handle  the  vast  stores  of  goods 
which  were  intended  to  be  shipped  to  the  Allies  and  to  the  Amer- 
ican forces  in  France.  Thus,  the  Allied  Provision  Export  Com- 
mission was  forced  to  reduce  its  orders  for  shipment  of  condensed 
milk  from  this  country  to  one  fourth  the  regular  monthly  amount 
and  the  American  government  ceased  ordering  additional  supplies 
of  condensed  milk  for  its  overseas  forces. 

In  the  meantime,  the  condensed  milk  firms  in  this  country 
had  contracted  for  an  increased  supply  of  fluid  milk  at  high 
prices  with  their  farmers,  many  new  factories  had  been  erected 
and  the  output  of  the  old  factories  was  vastly  increased.  With 
the  sudden  reduction  of  orders  from  the  Allies  and  the  complete 


160 


EXPORTS  AND  IMPORTS 


absence  of  orders  from  the  U.  S.  Government,  large  quantities 
of  condensed  milk,  produced  at  high  cost  began  to  stack  up  in 
our  factories,  causing  serious  fianancial  embarassment  to  the 
condensed  milk  concerns  and  placing  many  of  the  financially 
limited  companies  on  the  brink  of  disaster.  The  outlook  for  a 
rapid  increase  in  the  ocean-going  bottoms  during  the  summer  of 
1918  promises  to  permanently  relieve  this  temporarily  embarass- 
ing  situation  of  the  condensed  milk  industry. 

Commercial  Stocks  of  Condensed  Milk. — Bulletin  No.  7  of 
the  United  States  Food  Surveys1  shows  that  the  total  condensed 
milk  stocks  January  1,  1918,  amounted  to  310,881,660  pounds. 
Of  this  total  the  milk  condenseries  held  22.8  per  cent ;  the  storage 
warehouses,  7.7  per  cent;  the  wholesale  dealers,  35.4  per.  cent; 
and  the  retail  dealers,  27.2  per  cent.  The  remainder,  amounting 
to  6.9  per  cent  was  held  by  a  miscellaneous  group  of  firms. 

Stocks  of  Condensed  Milk  Reported  for  January  1,   1918,  with 
Comparative  Figures  for  Jan.  1,  1917,  by  Classes  of  Business. 


Class 
of 
Business. 

Total 
Stocks 
Reported 
for 
Jan.    1,    1918. 
Pounds. 

Comparative  Figures  from  Firms  Reporting 
for  both   1918   and   1917 

1918    Stocks. 

1917 
Stocks. 

Pounds. 

Pounds. 

Per    Cent 
of 

1917. 

Total 

310,881,660 

252,477,297 

143.3 

176,233,345 

Milk    Condenseries. 
Storage    Ware- 
houses   

70,825,746 

23,864,774 
4,502,077 
19,362,697 
110,198,428 

91,377,772 
11,220,326 

7,600,330 
84,575,145 
54,011,146 
29,791,437 

772,562 
21,417,567 

68,446,813 

10,769,896 
3,365,032 
7,404,864 
98,317,135 

82,642,228 
9,741,702 

5,933,205 
63,227,472 
39,980,275 
22,739,673 

507,524 
11,715,981 

252.8 

204.6 
668.6 
155.6 
121.9 

108.1 
368.4 

390.4 
110.5 
108.8 
113.1 

128.9 
194.9 

27,073,128 

5,262,791 
503,280 
4,759,511 
80,648,372 

76,484,205 
2,644,461 

1,519,706 
57,238,147 
36,746,660 
20,097,645 

393,842 
6,010,907 

Col^  Storages  
Warehouses    
Wholesale  Dealers. 
Wholesale 
Grocers    

Meat    Packers... 
Other  Wholesale 
Dealers    

Retail    Dealers  
Retail   Grocers... 
General  Stores.  .  . 
Other  Retail 
Dealers    

Miscellaneous    

1  Food  Surveys,  Bureau  of  Markets,  U.    S.  Department  of  Agriculture,  Vol. 
1,   No.   7.     Special   issue,   June,   1918. 


EXPORTS  AND  IMPORTS  161 

Exports  and  Imports. — Canned  condensed  milk  only  need 
be  considered  here. 

The  United  States  Bureau  of  Statistics  reports  the  following 
imports  and  exports  of  condensed  milk  for  the  years  1911  to 
1917  inclusive : 

Exports  and  Imports  of  Condensed  Milk  for  the  Years 
1911  to  1917,  inclusive.1 

Exports  Imports. 

Years  .  Pounds  Dollars  Pounds  Dollars 


1911 
1912 
1913 
1914 
1915 
1916 
1917 

12,180,445 
20,642,738 
16,525,918 
16,209,082 
37,235,627 
159,577,620 
259,102,213 

936,105 
1,651,879 
1,432,848 
1,341,140 
3,066,642 
12,712,952 
25,129,983 

630,308 
698,176 
1,778,044 
14,599,339 
33,624,189 
18,174,505 
18,375,698 

46,088 
61,671 
135,724 
1,089,440 
2,556,787 
1,515,354 
1^46,446 

Prior  to  1914  the  United  States  exported  condensed  milk 
chiefly  to  North  America,  Oceanica  and  Asia,  small  quantities 
were  also  exported  to  South  America,  Africa  and  Europe.  About 
60  per  cent,  of  all  the  export  condensed  milk  went  to  countries 
of  the  North  American  Continent,  Canada  and  Panama  being 
the  leading-  markets.  During  the  last  few  years,  immediately 
preceding  the  world  war,  our  exports  to  Canada  had  fallen  off 
very  rapidly.  In  1911  the  exports  to  Canada  amounted  to  only 
about  15  per  cent,  of  the  total  exports  of  condensed  milk  to  the 
same  country  in  1908.  The  rapid  development  of  the  milk  con- 
densing industry  in  Canada,  within  the  last  decade  was  largely 
responsible  for  this  situation.  From  1907  to  1911  there  was  an 
annual  decrease  in  the  total  exports  of  the  United  States.  In 
1907  they  amounted  to  $2,191,000.00  as  against  $936,105.00  in 
1911. 

Prior  to  1913,  the  imports  of  condensed  milk  into  the  United 
States  were  likewise  very  limited.  This  was  largely  due  to  the 
protective  tariff  on  imported  goods,  which  was  an  effective  agent 
to  exclude  foreign  brands  from  American  markets. 

1  United  States  Department  of  Commerce  and  Labor,  Bureau  of  Statistics  for 
1911  to  1917. 


162  CHEMICAL  COMPOSITION 

In  the  fall  of  1913,  Condensed  Milk  was  placed  on  the  "free 
list."  This  resulted  in  an  immediate  and  rapidly  growing  in- 
flux of  condensed  milk  from  European  countries,  such  as  Switzer- 
land, Denmark,  Holland,  Sweden,  Norway,  Germany  and  Eng- 
land. At  first  the  bulk  of  the  influx  consisted  of  sweetened  con- 
densed milk,  but  later  evaporated  milk  also  arrived  in  increasingly 
large  quantities,  causing  havoc  in  our  domestic  markets,  and 
almost  unprecedented  depression  in  the  industry  in«  the  Fall  of 
1914.  At  the  same  time,  the  exports  further  decreased  and  ceased 
almost  entirely. 

In  1915  the  food  shortage  in  the  allied  countries  and  their 
need  of  condensed  milk  for  their  armies  and  navies  began  to 
counteract  the  effect  of  the  removal  of  the  protective  tariff. 
Imports  rapidly  decreased  and  finally  ceased  almost  entirely, 
while  large  and  repeated  contracts  for  exports  to  the  Allies 
brought  about  an  unprecedented  growth  of  our  export  trade  of 
condensed  milk  at  attractive  prices.  Our  exports  were  further 
increased  by  the  fact  that  the  war  deprived  non-combatant 
countries  in  South  America,  Asia  and  Africa  of  their  usual 
imports  of  this  commodity  from  the  now  warring  countries, 
opening  up  the  world  markets  to  the  United  States. 

These  events  have  resulted  in  partial  elimination  of  foreign 
condensed  milk  from  our  domestic  markets  and  in  a  fifteen  fold 
increase  of  our  exports  of  condensed  milk  in  1917  over  1914. 


CHAPTER  XIX. 
CHEMICAL  COMPOSITION  OF  CONDENSED  MILK 

Sweetened  Condensed  Milk. — Sweetened  condensed  milk 
contains  all  the  constituents  of  fresh  milk  and  considerable  but 
varying  quantities  of  sucrose.  Its  composition,  therefore,  de- 
pends on  such  factors  as :  composition  of  the  fresh  milk  from 
which  it  is  made;  the  degree  of  condensation  and  per  cent,  of 
cane  sugar  added.  As  all  of  these  factors  vary  in  milk  from 
different  localities,  and  in  milk  of  the  same  factory  at  different 
seasons  of  the  year,  no  hard  and  fast  rule  can  be  given.  The 
following  figures  merely  show  the  average  composition  of  sweet- 


CHEMICAL  COMPOSITION  163 

ened  condensed  milk  as  obtained  from  the  results  of  analyses  of 
a  large  number  of  different  brands. 


Average  Composition  of  Sweetened  Condensed  Milk 

Water  26.5  per  cent, 

rfat  9.0  per  cent.^ 

7V/r,,1       ,.j         I  proteids  8.5  per  cent.  00 ,. 

Milk  solids.    <      •«  no  >         32.6  Per  cent- 

|  milk  sugar        13.3  per  cent.  C 

(^ash  1.8  per  cent.J 

Cane  sugar  40.9  per  cent. 

Total  100.0  per  cent. 

Water. — The  water  content  is  largely  governed  by  the  de- 
gree of  condensation  and  the  per  cent,  of  cane  sugar.  American 
brands  average  from  24  per  cent  to  28  per  cent  water.  In  ex- 
ceptional cases  milk  has  been  found  to  contain  as  low  as  21  per 
cent,  and  as  high  as  34  per  cent,  water. 

Milk  Solids. — The  per  cent,  of  milk  solids  is  largely  governed 
by  the  per  cent,  of  milk  solids  in  fresh  milk  and  the  degree  of 
condensation.  In  the  majority  of  brands  the  solids  fluctuate  be- 
tween 30  and  34  per  cent. ;  in  extreme  cases  analyses  have  shown 
as  low  as  28  per  cent,  and  as  high  as  40  per  cent,  milk  solids. 
The  relative  proportion  in  which  the  various  solid  constituents 
are  present  is  the  same  as  that  in  the  fresh  milk  from  which  the 
condensed  milk  is  made,  provided  that  the  fresh  milk  was  not 
skimmed  previous  to  condensing. 

Butterfat. — The  butter  fat  in  sweetened  condensed  whole 
milk  fluctuates  from  about  8  to  12  per  cent.,  according  to  locality, 
season  of  year  and  degree  of  condensation.  Sweetened  con- 
densed milk  sold  in  barrels  is  usually  partly  or  wholly  skimmed 
and  is,  therefore,  low  in  fat.  It  has  been  suggested  that  a  small 
portion  of  the  milk  fat  is  lost  during  the  process  of  condensation, 
and  this  theory  is  frequently  resorted  to  by  condensed  milk  men 
to  explain  why  their  milk  is  low  in  fat.  It  has  been  claimed  by 
some  that  the  volatile  fats  (volatile  fatty  acids)  are  lost  during  the 
process  of  condensation.  This  claim  is  not  well  founded,  since 


164  CHEMICAI,  COMPOSITION 

repeated  experiments1  have  conclusively  demonstrated  that  con- 
densed milk  contains  the  normal  amount  of  volatile  fatty  acids. 
It  has  f.urther  been  experimentally  proven  that  the  condensed 
milk,  when  made  properly  and  from  whole  milk,  contains  fat 
equal  in  amount  to  that  found  in  the  fresh  milk  used.  A  reason- 
able allowance  should  be  made,  however,  for  loss  of  milk  due  to 
spilling  and  wasting  in  pipes  and  retainers.  Experience  has 
shown  that  this  loss  amounts  to  about  fifty  to  one  hundred 
pounds  of  milk  per  average  batch  under  normal  conditions. 

Proteids. — The  per  cent,  of  proteids  in  the  condensed  milk 
varies  with  the  per  cent  of  proteids  in  the  original  milk 
and  the  degree  of  concentration.  It  fluctuates  usually  between 
7.5  and  9  per  cent.  The  heating  previous  to  condensing  coagul- 
ates a  portion  of  the  milk  albumin  and  alters  the  casein  to  the 
extent  that  it  is  not  precipitated  in  the  normal  way,  when  rennet 
is  added  to  the  diluted  condensed  milk.  In  early  spring  when 
the  majority  of  the  cows  supplying  the  condensery  freshen, 
there  is  a  tendency  of  the  jacket  and  coils  in  the  vacuum  pan  to 
become  coated  more  or  less  heavily  with  a  layer  of  semi-solid 
milk.  This  very  probably  is  due  to  the  relatively  high  per  cent, 
of  albumin  which  sticks  to  the  heating  surface.  This  thickened 
milk,  when  mixed  with  and  stirred  in  water,  usually  dissolves 
without  much  difficulty.  See  also  "Defects  of  Sweetened  Con- 
densed Milk,"  page  202. 

While,  in  most  analyses  of  sweetened  condensed  milk,  the 
per  cent,  of  proteids  nearly  equals  that  found  in  the  fresh  milk 
multiplied  by  the  degree  of  concentration,  there  is  a  tendency 
toward  a  slight  loss  of  this  constituent  due  to  precipitation  in 
the  forewarmers. 

Milk  Sugar. — Sweetened  condensed  milk  contains  from  about 
12.5  to  15  per  cent,  of  milk  sugar,  the  amount  varying  according 
to  the  degree  of  concentration  and  per  cent,  of  milk  sugar  in 
the  fresh  milk.  The  milk  sugar  is  not  known  to  undergo  any 
material  changes  as  the  result  of  the  condensing  process.  If 
condensed  milk  is  recondensed,  it  assumes  a  darker  color  which 
is  largely  due  to  the  caramelizing  of  a  part  of  the  milk  sugar, 
caused  by  the  action  of  prolonged  exposure  to  heat.  The  milk 


1  Hunziker   and    Spitzer,   Indiana   Agricultural   Experiment    Station    Bulletin 
No.  134,  1909. 


CHEMICAL  COMPOSITION  165 

sugar  in  condensed  milk  crystallizes  very  readily  and  causes  the 
condensed  milk  to  become  sandy  and  settled.  Chemical  ana- 
lyses of  this  sugar  sediment  show  that  it  consists  principally 
of  milk  sugar.  The  primary  cause  of  this  property  lies  in  the 
fact  that  sweetened  condensed  milk  contains  so  little  water 
(about  26.5  per  cent.)  that  the  milk  sugar  is  present  in  the  form 
of  a  supersaturated  solution ;  therefore,  any  condition  which 
favors  sugar  crystallization  will  tend  to  produce  this  defect.1 
Milk  sugar  requires  from  five  to  six  times  its  weight  of  water 
at  ordinary  temperatures  for  complete  solution.  In  sweetened 
condensed  milk  the  milk  sugar  has  access  to  only  about  twice 
its  weight  of  water  (12.5  to  15  per  cent  lactose  to  25  to  27  per 
cent,  water). 

Ash. — The  per  cent,  of  ash  is  largely  dependent  on  the 
degree  of  condensation.  It  usually  varies  from  1.5  to  2  per  cent. 
It  is  quite  constant  in  fresh  milk  (normal  fresh  milk  contains 
uniformly  about  .7  per  cent.  ash).  The  per  cent,  of  ash  in 
sweetened  condensed  milk  may  serve,  therefore,  as  a  reason- 
ably reliable  factor  in  determining  the  degree  of  condensation. 
The  heating  of  milk,  before  condensing,  precipitates  and  renders 
insoluble  a  portion  of  the  mineral  solids,  principally  the  lime 
salts. 

Sucrose. — The  purpose  of  the  presence  of  sucrose  in  this 
product  is  to  preserve  it.  Most  of  the  sweetened  condensed 
milk  on  the  market  contains  from  37  to  43  per  cent,  sucrose,  or 
cane  sugar.  Wider  variations,  however,  are  not  infrequent.  In 
some  cases  analyses  showed  as  low  as  30  per  cent,  and  in  others 
as  high  as  48  per  cent,  cane  sugar.  Cane  sugar  dissolves  in  one 
half  its  weight  of  water,  so  that  under  normal  conditions  there 
is  sufficient  water  in  the  condensed  milk  to  keep  the  sucrose 
in  solution.  The  amount  of  sucrose  in  milk  does  not  appreciably 
affect  the  power  of  the  milk  to  dissolve  milk  sugar,  nor  does 
the  per  cent  of  lactose  present  materially  affect  the  power  of  the 
milk  to  dissolve  sucrose. 

Specific  Gravity. — The  specific  gravity  of  sweetened  con- 
densed milk  falls  within  the  limits  of  1.24  to  1.35.  Foreign 


1  For   further   details    on    causes   of   settled    sweetened    condensed    milk    see 
Chapter  XXIII,  page  196. 


166 


CHKMICAI,  COMPOSITION 


brands  average  higher  in  specific  gravity  than  American  brands. 
The  specific  gravity  of  sweetened  condensed  milk  is  controlled 
by  the  degree  of  condensation,  the  per  cent,  of  fat  and  the  per 
cent,  of  cane  sugar.  Milk  condensed  at  the  ratio  of  about 
2.5  parts  of  fresh  milk  to  1  part  of  condensed  milk  and  contain- 
ing about  9  per  cent  fat  and  40  per  cent  cane  sugar,  has  a  specific 
gravity  of  about  from  1.28  to  1.29.  The  specific  gravity  of  sweet- 
ened condensed  skim  milk  may  go  as  high  as  1.35,  and,  if  it  con- 
tains an  excess  of  cane  sugar,  it  may  be  still  higher. 


Chemical  Analyses  of  Sweetened  Condensed   Milk  of  Eighteen 

Different  Brands 


Brand 

Milk 
solids 
per 
cent. 

Water 
per 
cent. 

Pat 
per 
cent. 

Pro- 
teids 
per 
cent. 

Lac- 
tose 
per. 
cent. 

Ash 
per 
cent. 

Sucrose 
per 
cent. 

1  "Silver  Spoon" 
Hires'  Condensed  Milk  Oo     . 

31  90 

28  68 

8  40 

9  12 

12  56 

1  91 

40  38 

3  "Eagle" 
Borden's  Condensed  Milk  Co  
2  "Reindeer* 
Truro  Condensefd  Milk  Co  _. 

«  "Tip  Top" 
Bordens'  Condensed  Milk  Co.  

31.08 
31.23 
36.57 

25.99 
27.33 
21.67 

8.72 
9.56 
10.07 

8.15 
8.32 
9  35 

12.35 
13.42 
15  00 

1.83 

1.80 
2  15 

42.93 
41.44 
41  76 

a  "Challenge" 
Borden's  Condensed  Milk  Co  r_ 
3  "Sweet  Clover" 
Mohawk  Condensed  Milk  Co.  .  .    . 

31.74 
32.84 

24.84 
24.07 

8.23 
9.31 

8.57 
871 

13.C2 
12  95 

1.92 

1  87 

43,42 

43  09 

3  "Arrow" 
Wisconsin  Condensed  Milk  Co  
3  "Blue  Bell" 
American  Condensed  Milk  Co\  
3  "Red  Cross" 
Mohawk  Condensed  Milk  Co. 

31.15 

35.56 
34  78 

26,83 
26.50 
27  14 

8.00 
9.31 
11  07 

8.49 
9.50 
7  92 

12.87 
14.80 
14  0** 

1.79 
1.95 
1  »7fl 

42.02 
37.94 

00    BC4 

3  "Rose" 
Borden's  Condensed  Milk  Co  

30.82 

24  76 

8  88 

8  06 

12  07 

1  81 

Af)    Qf 

8  "Magnolia" 
Borden's  Condensed  Milk  Co. 

31  98 

26  32 

8  64 

7  84 

13  50 

200 

An  AA 

3  "Rustic" 
Michigan  Condensed  Milk  Co 

30  00 

27  63 

8  60 

7\07 

10    fjT) 

1*0 

2  "^ilk  "Maid" 
Anglo-Swiss  Condensed  Milk  Co  
B  "Jubilee" 
The  Manitoba  Dairy  Co  

2  "Export" 
Baldwin  Condensed  Milk  Co.    _ 

35.69 
29.40 
32  24 

25.65 
32.15 
26  69 

9.65 
9.62 
11  50 

8.78 
8.61 
8  50 

15.17 
11.30 

12  35 

2.09 
1.85 
1  Aft 

38.66 

33.45 

4.1   Cfl 

a  «owi» 
Canada  Milk  Condensing  Co  _. 
2  "Nestle" 
Henry  Nestle      fc  . 

31.61 
32  91 

30.84 
28  04 

10.61 
8  06 

8.47 

7  68" 

12.40 
15  28 

1.81 

104 

37.55 

OQ    O5 

3  "Upper  Ten" 
U.  S.  Condensed  Milk  Co...  

33.65 

27.88 

8.80 

8.34 

14.66 

1.85 

3847 

1  Spitzer,  Indiana  Agricultural  Experiment  Station,   1910. 

2  McGill,  Inland  Rev.  Dept.,  Ottawa,  Bulletin  No.  144,  1908. 

8  Cochran,  Special  Report  of  Analysis  of  Condensed  Milks  and  Infants'  Foods, 
Pennsylvania  Department  of  Agriculture,  1905. 


CHEMICAI,  COMPOSITION 


167 


Evaporated  Milk. — The  same  factors  which  control  the 
chemical  composition  of  sweetened  condensed  milk,  also  govern 
that  of  the  unsweetened  product,  with  the  exception  that  the 
cane  sugar  is  absent. 

The  following  figures  represent,  in  round  numbers,  the 
average  composition  of  evaporated  milk  as  obtained  from 
analyses  of  a  large  number  of  American  brands. 


Water 


Milk  solids 


Average  Composition  of  evaporated  milk 


fat 

8.3  per  cent 

proteids 

7.5  per  cent 

lactose 

9.7  per  cent 

ash 

1.5  per  cent 

73  per  cent. 


27  per  cent. 


100  per  cent. 

The  chemical  and  physical  properties  of  the  various  ingredi- 
ents in  unsweetened  condensed  milk  are  affected  to  a  greater 
extent  than  in  the  case  of  sweetened  condensed  milk.  This  is 
largely  due  to  exposure  of  the  evaporated  milk  to  high  tempera- 
tures in  the  sterilizer. 

Water  and  Solids  are  governed  by  the  degree  of  concentra- 
tion and  the  relative  per  cent  of  the  same  constituents  in  the 
fresh  milk.  The  per  cent  of  solids  admissible  in  evaporated  milk 
is  largely  dependent  on  the  chemical  and  physical  properties  of 
the  milk  and  the  sterilizing  temperatures  employed.  Excess 
in  solids  in  this  product  jeopardizes  its  marketable  properties, 
owing  to  the  tendency  of  the  proteids  to  form  hard  lumps  of 
curd  during  the  sterilizing  process.  Evaporated  milk  very  low 
in  solids  tends  toward  the  separation  of  its  butter  fat  in  storage. 
Analyses  show  a  range  of  from  23  to  31  per  cent  solids.  Since 
the  per  cent  of  solids  necessary  and  possible  to  be  contained  in 
marketable  evaporated  milk,  largely  depends  on  the  properties 
of  milk,  and,  since  these  properties  again  are  principally  con- 
trolled by  locality,  season  of  year,  crop,  feed  and  weather  con- 
ditions and  the  quality  of  the  fresh  milk,  the  solids  in  milk  from 
any  given  season  of  the  year  may  vary  very  considerably.  In 


168 


CHEMICAL  COMPOSITION 


some  localities  and  at  certain  times  of  the  year  the  best  results 
may  be  obtained  with  evaporated  milk  containing  28  per  cent 
solids.  In  other  localities  it  may  be  difficult  at  certain  seasons 
of  the  year,  to  incorporate  more  than  24  per  cent  solids  without 
injuring  or  destroying  the  marketable  properties  of  the  product.1 
Butterfat. — The  fat  varies  with  the  per  cent  of  fat  in  the 
fresh  milk  and  with  the  degree  of  concentration.  No  fat  is  lost 
during  the  process  of  condensing  and  sterilizing.2  It  has  been 
claimed  by  some  that  in  the  process  of  manufacture,  the  volatile 
fatty  acids  escape  and  that  the  evaporated  milk  therefore  con- 
tains less  fat  than  the  fresh  milk  from  which  it  is  made,  times 
the  degree  of  concentration.  If  this  were  true  the  loss  of  fat  in 
the  evaporated  milk  would  not  exceed  .25  of  1  per  cent.  But 
analyses  show  that  the  fat  in  the  evaporated  milk  is  entirely 
normal  in  composition  and  contains  the  same  proportion  of 
volatile  fatty  acids  as  the  fat  in  the  fresh  milk. 

The  Composition  of  Milk  Fats  in  Evaporated  Milk2 


Date  of 
Manufacture 

Reichert 

Meissl 
number 

Iodine 
number 

Melting  point  of 
mixed  fats 

Melting  point  of 
insoluble 
fatty  acids 

\ugust    1908 

28  48 

33  64 

33  3  degrees  C 

41  0  degrees  C 

November,   1908    

29.52 

33.60 

33^4  degrees  C. 

41.2  degrees  C. 

In  the  evaporated  milk  there  is  a  strong  tendency  for  the 
fat  to  separate  out  during  storage  and  to  churn  in  transportation. 
This  is  largely  avoided  by  the  proper  adjustment  of  the  steriliz- 
ing process  and  by  use  of  the  homogenizer. 

Proteids. — (The  proteids  vary  with  the  per  cent  of  total 
proteids  in  the  fresh  milk  and  the  degree  of  concentration. 
Similar  to  the  case  of  sweetened  condensed  milk  there  is  a 
tendency  of  a  slight  loss  of  proteids  in  evaporated  milk  due  to 
mechanical  adhesion  of  a  part  of  the  precipitated  curd  to  the 
heating  surfaces  in  the  forewarmers  and  in  the  vacuum  pan. 

Most  of  the  coagulable  milk  albbumin  is  precipitated.  Fresh 
milk  contains  about  .16  per  cent  of  albumin  that  is  not  coagu- 
lable by  heat.3  The  relation  of  soluble  and  insoluble  curd  is 


1  Hunziker,  Indiana  Agricultural  Experiment  Station,  Twenty- first  Annual 
eP°rHunziker  and  Spitzer,  Indiana  Agricultural  Experiment  Station,  Bulletin 
°'  8  Hunziker,  Indiana  Agricultural  Experiment  Station,  Bulletin  No.  143. 


CHEMICAL  COMPOSITION 


169 


shown  in  the  following  table  which  represents  analyses  of  dif- 
ferent brands  of  evaporated  milk. 

Soluble  and  Insoluble  Curd  in   Evaporated  Milk1 


Brand 

Insoluble 
curd 
per  cent 

Soluble 
albumin 
per  cent 

Total 
proteids 
per  cent 

Gold   Milk  

844 

.46 

8.90 

Columbine    

7.41 

.49 

7.90 

Every   Day  

7.54 

.46 

8.0 

Gold  Milk 

737 

33 

770 

Star                  

786 

.30 

8.16 

Morning1    Glory  

828 

.34 

8.62 

Carnation    

6.49  * 

.52 

6.91 

Beauty    

8.39 

.39 

8.78 

Van  Camp's  

7.52 

.42 

7.94 

Monarch    

6.77 

.52 

7.29 

Diadem 

7.06 

.42 

7.48 

Reindeer 

6.88 

.52 

7.40 

Wilson's    .  .      . 

6.89 

.49 

7.38 

Dundee    

7.21 

.44 

7.65 

Average    

7.436 

.429 

7.865 

The  above  figures  show  that,  in  the  evaporated  milk,  prac- 
tically all  of  the  coagulable  albumin  is  changed  to  insoluble  curd. 
The  brands  analyzed  contained  evaporated  milk  condensed  at 
the  ratio  of  2  to  2.4  parts  of  fresh  milk  to  1  part  of  evaporated 
milk.  The  soluble  albumin  found  corresponds  with  the  albumin 
not  coagulable  by  heat,  normally  found  in  fresh  milk,  times  the 
ratio  of  concentration. 

The  casein  is  largely  precipitated  by  the  sterilizing  heat, 
but  is  present  in  the  form  of  very  finely  divided  particles.  This 
is  due  to  the  mechanical  shaking  to  which  the  evaporated  milk 
is  subjected  in  the  sterilizer  and  in  the  shaker.  In  many  batches 
of  evaporated  milk  the  precipitation  of  the  casein  during  sterili- 
zation is  so  fine  that  the  product  is  perfectly  smooth  without 


143. 


Hunziker,  Indiana  Agricultural  Experiment  Station,  Bulletins  No.   134  and 


170  CHEMICAI,  COMPOSITION 

shaking.    The  casein  in  evaporated  milk  does  not  respond  to  the 
action  of  rennet  as  does  the  casein  in  fresh  milk. 

Milk  Sugar. — The  milk  sugar  is  present  in  per  cent  corre- 
sponding with  that  of  the  original  milk,  times  the  degree  of  con- 
centration. A  portion  of  it  has  undergone  oxidation  (carameliza- 
tion)  due  to  the  high  sterilizing  temperatures.  It  gives  to  the 
evaporated  milk  a  yellow  to  light  brown  color.  The  higher  the 
sterilizing  temperature  and  the  longer  the  exposure  of  the  evapo- 
rated milk  to  this  heat,  the  darker  is  its  color. 

Ash. — The  mineral  constituents  also  are  present  in  nearly 
the  same  proportion  to  the  other  solids,  as  in  fresh  milk.  They 
are  largely  rendered  insoluble  by  the  sterilizing  process.  The 
lime  constituents  frequently  are  found  in  the  bottom  of  the  cans 
in  the  form  of  hard,  whitish,  insoluble  granules. 

Since  the  ash  in  normal  fresh  milk  is  practically  constant, 
averaging  about  .70  per  cent,  the  per  cent  of  ash  in  the  evapo- 
rated rnilk  is  frequently  used  as  a  factor  in  determining  the 
degree  of  concentration.  The  results  may,  however,  be  very 
misleading,  since,  when  the  ash  is  precipitated  in  the  form  of 
granules,  it  is  practically  impossible  to  mix  it  back  into  the  milk 
in  order  to  obtain  a  representative  sample  for  analysis. 

The  Specific  Gravity  ranges  from  1.05  to  1.08,  according  to 
the  degree  of  concentration  and  the  specific  gravity  of  the  original 
milk.  It  averages  about  1.065. 

Plain  condensed  bulk  milk  is  of  very  varying  composition, 
depending  largely  on  the  degree  of  concentration  and  the  per 
cent  of  fat  present.  It  is  usually  made  from  partly  or  wholly 
skimmed  milk  and  is  condensed  at  the  ratio  of  3  to  4  parts  of 
fresh  milk  to  1  part  of  condensed  milk.  The  same  fact  applies 
to  the  composition  of  concentrated  milk. 


CHEMICAL  COMPOSITION 


171 


Chemical  Analyses  of  Twenty-four  Different  Brands  of  Evapo- 
rated Milk1 


Brand 

Solids 

Water 

Eat 

Curd 

Lac- 
tose 

Ash 

Total 

Gold  Milk   

29.25 

7075 

942 

844 

975 

1  54 

9990 

Columbine  .... 
Every    Day...  . 
Gold    Milk  
Star 

24.63 
26.20 
27.18 
2904 

75.37 
73.80 
72.82 
7090 

7.45 
8.07 
9.07 
835 

7.41 
7.54 
7.39 
786 

8.56 
9.10 
9.23 
1037 

1.36 
1.47 
1.49 
1  62 

99.98 
100.15 
100.00 
99  16 

Morning   Glory 
Carnation    .... 
Beauty    

31.08 
23.81 
28.38 

68.92 
76.19 
7162 

10.48 
8.05 
847 

8.26 
6.49 
839 

10.47 

7.55 
994 

1.67 
1.24 
1  56 

99.82 
99.49 
9998 

Van    Camp's.  .. 
Wilson's    

27.89 
25.23 

72.11 

74.77 

8.69 
870 

7.52 
653 

9.66 
868 

1.54 
1  37 

99.52 
10005 

Monarch    

26.70 

73.30 

8.09 

677 

1035 

1  44 

9995 

Diadem 

2496 

7504 

816 

706 

792 

1  33 

9951 

Reindeer 

26.66 

73.34 

8.08 

688 

10.21 

145 

9996 

Dundee 

27.04 

7296 

873 

721 

936 

1  48 

9974 

Sundry  samples 
1 

28.02 

71.98 

8.93 

768 

986 

1  61 

10006 

2  

31.99 

68.01 

9.68 

849 

1.1.88 

1  69 

•9975 

3  

26.01 

73.99 

8.18 

6.77 

924 

1  46 

9964 

4 

2733 

7267 

904 

693 

942 

1  51 

9957 

5 

2937 

7063 

971 

734 

1052 

1  56 

9976 

6 

21  12 

7888 

7.30 

578 

678 

1  12 

9986 

7  

2325 

76.75 

798 

619 

7.96 

1  25 

100.13 

8  

25.48 

74.52 

8.68 

6.34 

8.67 

1  35 

99.56 

9  

26.62 

73.38 

9.20 

7.00 

9.18 

1.37 

100.13 

i  Hunziker  and   Spitzer,    Indiana  Agricultural   Experiment   Station,   Bulletin 
No.   134,  1909. 


172  SANITARY  PURITY 

CHAPTER  XX. 

SANITARY    PURITY    AND    DIETETIC    VALUE    OF 
CONDENSED   MILK 

Sanitary  Purity. — From  the  point  of  view  of  freedom  from 
pathogenic  and  other  harmful  micro-organisms,  all  forms  of  con- 
densed milk  are  superior  to  the  average  market  milk.  In  the 
first  place,  the  manufacture  of  a  marketable  condensed  milk 
makes  essential  eternal  vigilance  in  the  control  of  the  quality  of 
the  fresh  milk.  It  is  safe  to  state  that  in  no  milk  plants  does 
the  quality  of  the  fresh  milk  accepted,  receive  more  careful  atten- 
tion and  average  higher  than  in  the  milk  condensery.  The  foun- 
dation of  the  condensed  product,  the  fresh  milk,  therefore,  is  of 
a  relatively  high  standard  of  purity. 

Again,  the  temperature  to  which  the  milk  is  subjected  is  suf- 
ficiently high  to  destroy  the  germs  of  practically  all  milk-borne 
diseases;  so  that,  unless  the  condensed  milk  becomes  infected 
with  pathogenic  germs  after  condensing  and  before  the  tin  cans 
are  hermetically  sealed,  practically  all  danger  from  disease  germs 
is  eliminated.  In  the  case  of  evaporated  milk  the  marketable 
product  is  free  from  all  forms  of  germ  life.  The  only  exception 
to  this  rule  would  apply  to  concentrated  milk,  in  the  manufacture 
of  which  the  milk  is  not  heated  to  temperatures  detrimental  to 
the  life  of  bacteria. 

Dietetic  Value. — The  dietetic  value  of  condensed  milk  is 
largely  dependent  on  the  effect  of  heated  milk  on  its  nutritive 
value  and  on  digestion.  As  far  as  condensed  milk  is  concerned, 
there  are  no  available  data  that  would  throw  any  light  on  this 
subject.  The  results  of  feeding  experiments  with  heated,  pas- 
teurized or  sterilized  milk  vs.  raw  milk,  however,  may  furnish  a 
logical  guide  as  to  the  dietetic  effect  of  condensed  milk.  Milk  pas- 
teurized at  Jiigh  temperatures,  or  sterilized,  may  be  considered 
comparable,  as  far  as  the  effect  of  heat  is  concerned,  to  condensed 
milk. 

Doane  and  Price1  report  the  following  experimental  results : 
"Raw  milk  is  more  easily  digested  when  fed  to  calves  than  either 


1  Doane  and  Price,  Maryland  Agricultural  Experiment  Station,  Bulletin  No. 
77,  1901. 


DIETETIC  VALUE  173 

pasteurized,  or  cooked  milk.  Contrary  to  theory,  cooked  milk, 
when  fed  to  the  calves  used  in  these  experiments,  caused  violent 
scouring-  in  the  majority  of  trials.  A  majority  of  physicians  in 
charge  of  children's  hospitals  corresponded  with,  favored  the  use 
of  raw  milk  for  infants  when  the  milk  is  known  to  be  in  perfect 
condition,  but  favored  pasteurized  milk  under  ordinary  condi- 
tions. With  one  exception  all  the  physicians  corresponded  with, 
discouraged  the  use  of  cooked,  or  sterilized  milk  for  infant 
feeding." 

Rosenau*  states  that  "Comparative  observations  upon  in- 
fants under  the  same  conditions  show  that  they  flourish  quite  as 
well  upon  heated  milk  as  upon  raw  milk.  Laboratory  experi- 
ments as  well  as  chemical  observations  coincide  with  the  view, 
that  heated  milk  is  quite  as  digestible  as  raw  milk.  In  fact  it  is 
now  claimed  to  be  more  so.  Metabolism  experiments  indicate 
that  the  utilization  of  calcium  and  iron  in  the  body  is  more  com- 
plete in  children  fed  upon  boiled  cow's  milk,  than  in  those  fed 
upon  raw  cow's  milk." 

Stutzer1  who  conducted  experiments  of  artificial  digestion 
reports  in  favor  of  boiled  milk,  while  similar  investigations  made 
by  Ellenberger  and  Hofmeister2  showed  no  difference  in  the 
digestibility  between  raw  and  cooked  milk. 

Rodet3  who  experimented  with  dogs  noticed  a  slight  dif- 
ference in  favor  of  boiled  milk.  Bruning4  fed  dogs,  pigs,  rabbits, 
and  guinea  pigs  with  raw  and  sterilized  milk  and  reports  that 
all  results  were  in  favor  of  the  sterilized  milk.  Bruckler's5  ex- 
periments with  dogs  showed  that  the  animals  gained  more  in 
weight  on  sterilized  milk  than  on  raw  milk,  but  that  their  general 
health,  vigor  and  vitality  was  better  when  fed  raw  milk.  Variot0 
observed  no  difference  in  the  effect  on  infants  between  raw  and 
boiled  milk. 

Peiper  and  Eichloff  made  post  mortem  examinations  on  num- 
erous dogs  which  had  been  fed  for  prolonged  periods  on  raw 


*  Rosenau,  United  States  Department  of  Agriculture,  Bureau  of  Animal  In- 
dustry, Circular  No.  153,  1910. 

1  Stutzer,  Landw.  Versuchs-Stationen,  40,  p.  307. 

2  Ellenberger  &  Hofmeister,   Bericht  ueber  das  Veterinarwesen  Koenigreich 
Sachsen,  1890. 

3  Rodet,  Compt.  rend.  soc.  biol.,  48,  p.  555. 

4  Bruning,  Muenchner  Mediz.,  Wochenschrift,  No.  8,  1905. 

*  Bruning,  Zeitschrift  fuer  Tiermed,  10,  p.  110,  1906. 

6  Bruckler,  Jahrbuch  fuer  Kinderheilk,  66,  p.  343,  1907. 
6  Variot,  Comp.  rend.,  139,  p.  1002,  1904. 


174  DIETETIC  VALUE 

and  boiled  milk,  respectively.  In  the  dogs  fed  on  boiled  milk 
the  marrow  of  the  bones  was  highly  anaemic,  the  articulation  of 
the  bony  structure  looser,  the  ash  content  of  the  bones  and  the 
blood  lower,  and  there  was  more  sodium  chloride  and  less  fibrin 
in  the  blood  than  in  the  case  of  the  dogs  fed  on  raw  milk. 

Storck*  and  others  attribute  such  infantile  diseases  as  rickets 
and  scurvy  to  the  feeding  of  boiled  milk. 

It  is  generally  assumed  that,  because  the  lime  and  phosphoric 
acid  of  milk  become  largely  insoluble  when  milk  is  heated  to 
sterilizing  temperatures,  these  elements  in  sterilized  milk  are 
not  sufficiently  available  to  supply  the  needs  of  the  growing 
organism.  In  experiments  with  dogs  Aron  and  Frese**  found 
that  the  utilization  of  the  lime  is  not  affected  by  heating  the  milk 
and  that,  as  far  as  the  assimilation  of  the  lime  by  the  growing 
organism  is  concerned,  it  is  immaterial  in  what  form  the  lime  is 
present.  Even  when  fed  in  difficultly  soluble  form,  as  tertiary 
lime  phosphate,  the  lime  was  utilized  as  well  as  the  lime  of 
normal  raw  milk. 

The  fact  that  the  phosphorus  (phosphoric  acid),  needed  for 
the  building  up  of  the  bony  structure,  and  which  is  present  in 
milk  largely  in  organic  combination  as  casein  and  as  lecithin,  is 
changed  by  heat  to  inorganic  combinations,  the  lecithin  phos- 
phorus by  saponification,  and  the  casein  phosphorus  by  changes 
in  the  casein  molecule,  suggests  a  poorer  retention  of  the  in- 
organic phosphorus  by  the  animal  body.  Cronheim  and  Mueller1 
who  studied  this  phase  of  nutrition  could  detect  no  appreciable 
difference  as  to  the  assimilation  of  phosphorus  by  feeding  ste- 
rilized and  raw  milk,  respectively.  Their  results  were  rather  in 
favor  of  sterilized  milk. 

Grimmer2  holds  that  digestive  and  intestinal  disorders  in  in- 
fants are  possibly  largely  due  to  biological  disturbances,  modify- 
ing the  bacterial  flora  of  .the  intestines,  and  to  the  absence  of 
lecithin  and  unorganized  ferments  in  heated  milk.  He  reports 
that  the  addition  to  boiled  milk  of  substances  rich  in  lecithin, 
such  as  the  yolk  of  egg,  also  ferments,  such  as  pepsin,  trypsin, 
and  emulsin  produce  a  marked  improvement  in  such  cases. 


*  Storck,  zit.  n.  Knusel,  Studien  ueber  die  sog.  sterilisierte  Milch  des  Han- 
dels.  Diss.,  Luzern,   1908. 

**  Aron  and  Frese,  Grimmer  Chemie  u.  Physiologic  der  Milch,  1910. 

1  Cronheim  and  Mueller,  Jahrbuch  fuer  Kinderheilk,  57,  p.  45,  1903. 

2  Grimmer,  Chemie  and  Physiologic  der  Milch,  1910. 


DIETETIC  VAUJE  175 

The  foregoing  citations  suggest  that  our  knowledge  of  the 
dietetic  effect  of  heated  or  boiled  milk  is  exceedingly  limited  and 
that  the  results  obtained  and  conclusions  drawn  by  the  various 
investigators  are  at  variance.  In  experiments  with  the  living 
organism,  and  confined  to  so  few  specimen  as  seems  to  have  been 
the  case  in  the  work  reported,  the  factors  of  individuality  and 
environment  are  a  constant  stumbling  block,  magnifying  the 
limit  of  experimental  error  and  weakening  the  conclusiveness  of 
the  results.  On  the  basis  of  our  present  knowledge  it  seems 
reasonable  to  conclude  that,  as  far  as  the  digestibility  of  its 
inherent  ingredients  is  concerned,  condensed  milk,  when  con- 
sumed in  properly  diluted  form,  varies  but  little,  if  any,  from 
raw  milk.  The  absence  in  condensed  milk  of  ferments,  such  as 
en-zymes,  which  are  destroyed  in  the  process  and  which  may 
assist  digestion,  may  be  considered  the  most  important  defect 
of  condensed  milk  from  the  dietetic  point  of  view. 

In  the  case  of  sweetened  condensed  milk,  however,  the  nutri- 
tive ratio  of  the  normal  milk  is  decisively  disturbed  by  the  pre- 
sence of  large  quantities  of  sucrose.  Even  when  diluted  to  far 
beyond  the  composition  of  normal  and  original  fluid  milk,  the 
per  cent,  of  cane  sugar  is  still  high,  causing  the  nutritive  ratio 
of  such  milk  to  be  abnormally  wide  and  unbalanced.  The  carbo- 
hydrates are  present  far  in  excess  of  the  protein,  fat  and  ash. 
If  fed  to  infants  exclusively  and  for  a  prolonged  period  of  time, 
the  growing  organism  is  bound  to  suffer  from  malnutrition  and 
at  the  expense  of  muscular  development. 

Furthermore,  it  is  conceded  by  the  medical  profession  that 
sucrose  is  not  a  suitable  form  of  carbohydrates  for  infants.  It 
js  not  as  digestible  as  lactose,  it  changes  the  bacterial  flora  of  the 
intestines,  enhancing  the  development  of  butyric  acid  and  other 
gas-forming  and  putrefactive  germs  at  the  expense  of  Bacillus 
bifidus,  which  is  the  natural  inhabitant  of  the  intestine  in  normal, 
milk-fed  babies. 

vSweetened  condensed  milk  is  generally  highly  advertised  by 
the  manufacturer  as  a  suitable  food  for  babies;  it  is  frequently 
recommended  by  physicians  and  in  some  instances,  it  is  claimed 
to  have  agreed  with  babies  who  were  unable  to  take  care  of  milk 
in  any  other  form.  It  is  not  improbable  that  in  these  extremely 
isolated  cases  of  baby  feeding,  when  all  other  feeds  failed,  the 


176  GROWTH-PROMOTING  AND  CURATIVE:  PROPERTIES 

true  virtue  attributed  to  the  sweetened  condensed  milk,  lay  in 
the  fact  that  the  mothers  carefully  followed  the  directions  on 
the  label  for  dilution.  The  directions  specify  that  the  condensed 
milk  be  diluted  with  ten  to  sixteen  parts  of  water.  The  majority 
of  cases  of  digestive  disorders  in  bottle-fed  babies  are  un- 
doubtedly the  result  of  the  natural  tendency  of  the  mother  to 
feed  her  child  too  much  milk  or  too  rich  milk.  When  we  con- 
sider that  the  ratio  of  concentration  in  swreetened  condensed  milk 
is  only  about  2.5  to  1,  it  is  obvious  that  a  dilution  of  10  or  16  to 
1  is  a  great  relief  to  the  over-taxed  digestive  organs  of  infants, 
previously  fed  on  milk  too  rich  for  normal  digestion.  The  im- 
mediate change  of  the  health  and  disposition  of  these  babies  for 
the  better,  as  the  result  of  turning  from  a  prolonged  siege  of 
too  rich  food  to  the  very  dilute  condensed  milk,  is  therefore  not 
surprising. 

The  manufacturer  of  sweetened  condensed  milk  in  this 
country  is  inclined  to  load  his  product  excessively  with  sucrose. 
He  does  this  largely  in  an  effort  to  increase  the  keeping  quality 
and  to  guard  against  the  development  of  fermentations  in  the 
finished  article  that  ruin  the  goods  for  the  market.  While  a 
certain  amount  of  sucrose  is  necessary  to  preserve  this  milk,  yet, 
if  the  product  is  manufactured  from  a  good  quality  of  fresh  milk, 
as  it  should  be,  and  when  the  proper  sanitary  conditions  are 
maintained  in  all  departments  of  the  factory,  sixteen  pounds  of 
cane  sugar  per. one  hundred  pounds  of  fresh  milk  is  entirely 
sufficient.  He  should  bear  in  mind  that  sweetened  condensed 
milk  is  used  and  accepted  by  the  consumer  as  a  substitute  for 
market  milk,  and  it  is  the  manufacturer's  moral  duty  to  retain 
in  this  substitute  the  normal  properties  and  composition  of  the 
product  which  it  is  supposed  to  replace,  as  nearly  as  is  consistent 
with  the  production  of  a  wholesome  and  marketable  product. 

Growth-Promoting  and  Curative  Properties.1 — Recent  dis- 
coveries by  Hart  of  the  University  of  Wisconsin,  McCollum 
and  Davis,  formerly  of  the  University  of  Wisconsin  and  now 
at  John  Hopkins  University.  Osborne  &  Mendell  of  Yale 
University  and  other  eminent  nutrition  experts  have  demon- 
strated, that  before  complete  growth  can  occur  in  a  young 
animal,  or  for  prolonged  maintenance,  or  for  the  preven- 

i  Journal  of  Biological  Chemistry  1913  to  1917. 


GROWTH-PROMOTING  AND  CURATIVE  PROPERTIES  177 

tion  of  certain  diseases,  the  diet,  besides  being  adequate  as 
regards  its  content  of  proteins,  carbohydrates,  fats  and  salts, 
must  contain  certain,  at  present  unidentified  accessory  sub- 
stances. These  substances  are  of  two  classes,  namely  those  that 
are  fat-soluble,  and  those  that  are  water-soluble.  The  absence 
in  the  diet  of  either  or  both  of  these  accessory  substances  causes 
stunting  of  growth  and  the  development  of  certain  characteristic 
diseases. 

In  the  absence  of  the  fat-soluble  accessory  substance  the 
diet  produces  certain  diseases  of  which  sore  eyes  and  ultimate 
blindness  are  characteristic.  In  the  absence  of  the  water-soluble 
accessory  substance,  the  diet  gives  rise  to  the  disease  of  beriberi. 
In  either  case,  normal  growth  is  not  obtained,  the  whole  organism 
is  stunted,  and  the  cycle  of  life  is  abbreviated. 

The  fat-soluble  substance  for  man  is  most  readily  available 
in  the  butterfat  of  milk,  in  egg  fat,  and  in  cod  liver  oil.  It  is  not 
contained  in  the  ordinary  animal  fats  such  as  lard  nor  in  any  of 
the  vegetable  fats.  It  is  also  found  in  the  leaves  of  plants,  but 
these  are  not  consumed  in  the  normal  diet  of  man  in  sufficient 
quantities  to  supply  the  necessary  amount  of  the  fat-soluble 
accessory  substances. 

The  water-soluble  accessory  substances  are  present  in  a 
larger  variety  of  foods  and  are  known  to  constitute  a  part  of  the 
skim  milk  portion  of  milk. 

It  is  obvious  from  the  above  that  milk  furnishes  not  only 
the  required  protein,  carbohydrates,  fats,  and  salts,  but  it  also 
supplies  these  fat-  and  water-soluble  accessory  substances,  which 
are  so  indispensible  to  the  normal  and  full  development  of  the 
young,  which  make  for  full  stature  of  the  adult  and  which  keep 
the  individual  and  the  race  in  healthy  condition. 

Condensed  milk  made  from  whole  milk  is  in  no  way  robbed 
of  these  accessory  elements.  The  heat  to  which  the  condensed 
milk  is  subjected  in  the  process  of  manufacture  neither  destroys 
nor  weakens  them  so  far  as  experimental  data  now  available 
show.  This  is  true  of  all  kinds  of  condensed  milk  and  evaporated 
milk  made  from  whole  milk.  From  the  standpoint  of  these 
growth-promoting  and  curative  properties,  all  forms  of  condensed 
milk  are,  therefore,  equally  desirable  for  infant  feeding,  for  child- 
ren and  for  the  adult,  as  is  whole  milk. 


178  CONDENSED  MILK  STANDARDS  AND  LAWS 

On  the  other  hand,  skim  condensed  milk  is  not  a  satisfactory 
food  for  the  growing  young.  It  lacks  the  indispensible  fat- 
soluble  accessory  and  unless  supplemented  by  egg  yolk,  cod 
liver  oil,  or  butter,  its  consumption  by  the  young  in  the  place  of 
whole  milk,  or  in  the  place  of  condensed  milk  made  from  whole 
milk,  will  prove  disastrous  to  the  growth  and  well-being  of  those 
who  are  restricted  to  such  a  diet. 

Nor  does  imitation  condensed  milk,  such  as  the  "Hebe" 
product,  in  which  the  butterfat  has  been  replaced  by  a  vegetable 
fat,  supplement  the  lacking  fat-soluble  accessory  substance.  The 
public  should  clearly  understand  that  in  milk  or  condensed  milk, 
there  is  no  substitute  for  butterfat  and  when  the  butterfat  is 
removed  the  product  no  longer  can  take  the  place  of  milk.  See 
also  "Addition  of  Artificial  Fats,"  page  230. 

CHAPTER  XXL 
CONDENSED  MILK  STANDARDS  AND  LAWS 

The  Federal  Food  and  Drugs  Act,  passed  June,  1906,  and 
which  went  in  force  January  1,  1907,  has  raised  the  standard  of 
excellence  of  condensed  milk  to  no  small  degree.  It  has  served 
as  a  purifier  of  the  entire  industry  putting  a  premium  on  the 
product  of  the  honest  manufacturer  and  insuring  the  public 
against  condensed  milk  of  inferior  food  value. 

Prior  to  the  enforcement  of  this  act,  three  states  only  had 
definite  standards  and  laws  regulating  the  composition  of  con- 
densed milk.  In  the  absence  of  a  federal  law,  car  loads  of  con- 
densed skim  milk  were  unloaded  and  sold  as  condensed  milk  in 
states  and  cities  which  had  no  laws  or  ordinances  prohibiting 
the  sale  of  condensed  skim  milk,  labeled  condensed  milk.  The 
Federal  Food  and  Drugs  Act.  executed  through  the  offices  of 
the  Interstate  Commerce  Department,  put  a  stop  to  this  fraud, 
protecting  the  public  from  these  inferior  goods,  eliminating  the 
manufacture,  traffic  and  competition  of  an  unlawful  product, 
enhancing  the  business  of  legitimate  manufacture  and  raising 
the  standard  and  integrity  of  the  industry. 

Federal  Standards.1 — The  Federal  Standards  for  sweetened 

i  United   States   Department   of   Agriculture,    Circular   No.    19;    also   Indiana 
Agricultural  Experiment  Station  Bulletin  No,  143. 


CONDENSED  MILK  STANDARDS  AND  LAWS  179 

condensed    milk    and    evaporated    milk    which    went    into   force 
January  1,  1907,  are  as  follows: 

"Sweetened  Condensed  Milk  is  milk  from  which  a  consider- 
able portion  of  water  has  been  evaporated  and  to  which  sugar 
(sucrose)  has  been  added  and  contains  not  less  than  28  (twenty- 
eight)  per  cent  of  milk  solids,  of  which  not  less  than  27.5  (twenty- 
seven  and  five-tenths)  per  cent  is  milk  fat." 

This  standard  for  milk  solids  in  sweetened  condensed  milk 
is  reasonable,  just,  adequate  and  attainable  under  all  normal 
conditions.  Sweetened  condensed  milk  in  hermetically  sealed 
tin  cans  averages  about  32  per  cent  milk  solids,  and  the  per  cent 
of  milk  solids  can  be  increased  considerably  above  this  average 
without  injuring  the  marketable  properties  of  the  product.  Manu- 
facturers of  sweetened  condensed  milk  well  know  from  costly 
experience,  that  it  would  not  do  to  drop  the  per  cent  of  milk 
solids  to  or  below  28  per  cent.  Such  milk  would  be  too  thin  to 
hold  the.  sugar  in  suspension,  the  sugar  would  tend  to  settle  to 
the  bottom  of  the  cans,  rendering  the  product  unsalable,  though 
not  necessarily  unwholesome.  Again,  this  thin  milk  does  not 
keep  well,  it  is  prone  to  undergo  fermentation.  The  manu- 
facture of  a  good  quality  of  salable  sweetened  condensed  milk 
requires  that  the  fresh  milk  be  condensed  at  the  ratio  of  about 
2£:1.  With  this  ratio  of  concentration  it  is  obvious  that  it  is 
not  difficult  to  incorporate  28  per  cent,  or  over,  of  milk  solids 
in  sweetened  condensed  milk  at  all  times. 

The  Federal  requirement  of  butterfat  in  sweetened  con- 
densed milk,  i.  e.  that  not  less  than  27.5  per  cent  of  the  total  milk 
solids  be  milk  fat,  is  also,  in  most  cases  attainable.  In  localities, 
however,  where  the  factory  is  supplied  almost  exclusively  writh 
low-testing  milk,  such  as  Holstein  milk,  there  is  danger  of  the 
product  falling  below  the  above  standard  in  butterfat  content 
at  times.  Eckles1  reports  that  the  butterfat  in  milk  from  Hol- 
stein cows  kept  by  American  Experiment  Stations  averaged 
28  per  cent  of  the  total  solids.  This  fact  can  leave  no  doubt  that, 
while  some  of  the  Holstein  milk  shows  a  higher  ratio  of  fat,  a 
considerable  portion  of  the  Holstein  milk  produced  must  neces- 
sarily contain  considerably  less  than  28  per  cent  of  fat  in  the 


1  Eckles— Dairy  Cattle  and  Milk  Production,  P.  33,  1911. 


180  CONDENSED  MILK  STANDARDS  AND  LAWS 

total  solids.  In  such  cases,  therefore,  it  would  be  necessary,  in 
order  to  meet  the  above  fat  standard,  to  reinforce  the  natural 
milk,  as  produced  by  the  cow,  by  the  addition  of  cream  or  butter. 

From  the  standpoint  of  the  ready  and  efficient  enforcement, 
such  a  standard  again  has  its  difficulty.  In  order  to  determine 
accurately  whether  the  fat  content  in  the  finished  product  repre- 
sents 27.5  per  cent  of  the  total  milk  solids,  it  is  necessary  to  also 
determine  accurately  the  per  cent  of  milk  solids,  and  this  in  turn 
means  the  determination  of  the  per  cent  sucrose.  But  experience 
has  amply  demonstrated  that  in  sweetened  condensed  milk,  con- 
taining both  lactose  and  sucrose,  it  is  exceedingly  difficult  to 
correctly  separate  these  sugars  for  accurate  quantitative  analysis. 

For  these  reasons,  therefore,  the  author,1  in.  1910,  recom- 
mended that  the  standard  for  sweetened  condensed  milk  be 
changed  to  28  per  cent  milk  solids  and  8  percent  fat;  and  this 
change  became  effective  in  1917,  as  per  Food  Inspection  Decision 
170,2  which  reads  as  follows: 

"Sweetened  condensed  milk,  sweetened  evaporated  milk, 
sweetened  concentrated  milk,  is  the  product  resulting  from  the 
evaporation  of  a  considerable  portion  of  the  water  from  the 
whole,  fresh,  clean,  lacteal  secretion  obtained  by  the  complete 
milking  of  one  or  more  healthy  cows,  properly  fed  and  kept,  ex- 
cluding that  obtained  within  fifteen  days  before  and  ten  days 
after  calving,  to  which  sugar  (sucrose)  has  been  added.  It  con- 
tains, all  tolerances  being  allowed  for,  not  less  than  twenty-eight 
per  cent  (28%)  of  total  milk  solids,  and  not  less  than  eight  per 
cent  (8%)  of  milk  fat. 

The  Federal  Standard  for  Evaporated  Milk  which  went  in 
force  January  1,  1907,  reads  as  follows: 

"Evaporated  Milk  is  milk  from  which  a  considerable  portion 
of  water  has  been  evaporated  and  contains  not  less  than  28 
(twenty-eight)  per  cent  milk  solids,  of  which  not  less  than  27.5 
(twenty-seven  and  five-tenths)  per  cent  is  milk  fat." 

Unfortunately,  for  the  moral  effect  of  the  law  and  for  the 
progress  of  the  condensing  industry,  the  standard  of  evaporated 
milk  was  made  so  high,  evaporated  milk  shall  contain  28  per  cent 
solids,  that  it  was  found  to  be  beyond  the  reach  of  the  manu- 

1  Hunziker,  Indiana  Agricultural  Experiment  Station  Bulletin  No.  143,  1910. 

2  U.  S.  Dept.  of  Agr.  Food  Inspection  Decision  170,  March  31,  1917. 


CONDENSED  MILK  STANDARDS  AND  LAWS  181 

facturer  to  comply  with  it  under  most  conditions  without  im- 
pairing the  marketable  properties  of  the  product.  The  results 
of  this  error  have  confronted  many  an  honest  manufacturer  with 
unsurmountable  difficulties.  He  was  compelled  to  choose  be- 
tween two  equally  unsatisfactory  alternatives,  i.  e.,  either  to 
manufacture  a  product  below  standard,  violating  the  law,  or  to 
close  his  factory. 

Modified  Evaporated  Milk  Standard. — The  unreasonableness 
of  the  Federal  Standard  for  evaporated  milk  was  experimentally 
demonstrated  by  results  of  investigations  conducted  at  the 
Indiana  Agricultural  Experiment  Station.1  Further  extensive 
investigations  were  made  by  the  United  States  Bureau  of 
Chemistry.2  Finally,  in  March,  191 1,3  the  standard  was  modified 
to  read  as  follows : 

"1.  Evaporated  milk  should  be  prepared  by  evaporating 
fresh,  pure  whole  milk  of  healthy  cows,  obtained  by  complete 
milking  and  excluding  all  milkings  within  fifteen  days  before 
calving  and  seven  days  after  calving,  provided  that  at  the  end 
of  this  seven  day  period  the  animals  are  in  a  perfectly  normal 
condition. 

"2.  It  should  contain  such  percentages  of  total  solids  and 
of  fat  that  the  sum  of  the  two  shall  be  not  less  than  34.3  and  the 
percentage  of  fat  shall  be  not  less  than  7.8  per  cent. 

"3.  It  should  contain  no  added  butter  or  butter  oil  incor- 
porated either  with  whole  milk  or  skimmed  milk  or  with  the 
evaporated  milk  at  any  stage  of  manufacture." 

This  modified  standard  was  an  improvement  over  the  origi- 
nal standard  which  it  superseded.  However,  the  requirements 
of  solids  were  still  too  high. 

Difficulties  of  Meeting  These  Standards  for  Evaporated 
Milk. — While  these  standards  can  be  complied  with  in  some 
localities  and  under  certain  favorable  conditions,  they  are  beyond 
the  reach  of  the  manufacturer  in  other  localities  and  under  less 
favorable  conditions.  The  manufacturer  is  compelled,  in  order 
to  produce  a  marketable  product,  to  use  sufficiently  high  tem- 


1  Hunziker,  Indiana  Agricultural  Experiment  Station  Bulletin  No.  143,  1910. 

2  Results  not  published. 

3  United  States  Department  of  Agriculture,  Food  Inspection  Decision  No.  131, 
1911. 


182  CONDENSED  MII,K  STANDARDS  AND  LAWS 

peratures  in  the  sterilizer  to  render  the  milk  absolutely  sterile. 
This  he  must  accomplish  without  causing  the  product  to  become 
curdy. 

The  degree  of  concentration  of  the  evaporated  milk  directly 
controls  its  curdling  properties.  The  higher  the  degree  of  con- 
centration, the  greater  is  the  danger  of  a  curdy  product.  Unfortu- 
nately, many  of  the  agents  which  regulate  the  ease  with  which 
milk  curdles,  are  not  under  the  control  of  the  operator.  They  have 
to  do  with  breed,  period  of  lactation,  condition,  care  and  feed 
of  the  cows,  season  of  year,  climatic  and  weather  conditions  and 
the  care  and  chemical,  physical  and  physiological  properties  of 
the  milk  on  the  farm.  It  so  happens  that  in  localities,  where 
dairying  has  not  as  yet  reached  a  high  state  of  development, 
where  cows  are  exposed  to  inclement  weather,  or  in  the  southern 
tier  of  the  dairy  belt,  where  the  cows  suffer  from  the  sweltering 
heat  of  the  summer  months  and  are  pestered  with  flies,  and 
where  the  available  water  for  cooling  the  milk  on  the  farm  is 
not  very  cold,  the  milk  is  more  prone  to  curdle,  than  in  highly 
developed  dairy  countries,  or  in  localities  of  the  cooler  regions 
of  the  dairy  belt,  etc. 

The  properties  of  milk  to  curdle,  whatever  the  agents  caus- 
ing them  may  be,  are  intensified  by  the  degree  of  concentration. 
It  is,  therefore,  necessary  for  the  successful  manufacture  of  a 
salable  product  to  regulate  this. 

A  further  objection  to  both,  the  original  and  the  modified 
standard  for  evaporated  milk  is  that,  where  milk  is  bought  and 
paid  for  on  the  basis  of  butterfat  contained  therein,  as  it  should 
be,  the  factory  receiving  high-testing  milk,  labors  financially 
under  a  distinct  disadvantage.  The  reason  for  this  is  that  in 
high-testing  milk,  such  as  Jersey  and  Guernsey  milk,  the  butter- 
fat  constitutes  about  34  per  cent  of  the  total  solids,  while  in  low- 
testing  milk,  such  as  Holstein  milk,  the  butterfat  constitutes  only 
about  28  per  cent  of  the  total  solids.  In  order  to  meet  the  require- 
ments for  milk  solids,  more  butterfat  has  to  be  put  into  the 
evaporated  milk  per  case,  where  high-testing  milk  is  condensed 
than  in  the  case  of  low-testing  milk.  Consequently,  the  cost  per 
case,  of  the  manufacture  of  such  milk  is  greater  than  that  of  low- 
testing  milk.  These  standards,  therefore,  discriminate  in  favor 


CONDENSED  MILK  STANDARDS  AND  LAWS  183 

of  manufacturers  and  breeds  of  low-testing  milk,  such  as  milk 
from  Holsteins  and  Ayrshires,  and  against  manufacturers  and 
breeds  of  high-testing  milk,  such  as  milk  from  Jerseys  and 
Guernseys. 

Putting  the  Composition  of  the  Evaporated  Milk  on  the  Label. 

— As  the  result  of  these  difficulties,  numerous  manufacturers 
protested  against  these  standards  and  succeeded  in  obtaining 
from  the  Government  temporary  concessions  to  the  effect  that 
"there  would  be  no  violation  of  the  Food  and  Drugs  Act  if  the 
percentage  composition  of  the  goods  was  plainly  stated  on  the 
label  in  connection  with  the  name  of  the  substance,  although 
this  might  be  lower  than  that  required  by  Food  Inspection  De- 
cision No.  131."  This  information  was  issued  by  the  Government 
to  the  condenseries  in  the  form  of  a  circular  letter. 

As  the  result  of  this  concession,  many  condenseries,  which 
experienced  difficulties  in  complying  with  the  original  standard, 
adopted  individual  standards  of  composition  in  accordance  with 
their  local  conditions  and  they  stated  on  the  label,  in  more  or 
less  legible  type,  the  percentages  of  solids  and  fat  below  which 
their  goods  would  not  drop. 

Subsequent  investigations  by  the  Government,  however, 
seemed  to  indicate  that  this  form  of  labeling  was  misleading  to 
the  public  and  would,  therefore,  be  in  violation  of  the  Food  and 
Drugs  Act.  Consequently,  the  concession  of  permitting  indi- 
vidual standards  was  then  withdrawn. 

The  Federal  Board  of  Food  Inspection  continued  to  further 
consider  the  advisability  of  modifying  the  evaporated  milk 
standard,  and  finally  decided  on  the  following  standard  for  evapo- 
rated milk,  which  is  now  in  force  and  which  became  effective 
April  2,  191 5  :x 

Condensed  milk,  evaporated  milk,  concentrated  milk,  is  the 
product  resulting  from  the  evaporation  of  a  considerable  portion 
of  the  water  from  the  whole,  fresh,  clean,  lacteal  secretion  ob- 
tained by  the  complete  milking  of  one  or  more  healthy  cows, 
properly  fed  and  kept,  excluding  that  obtained  within  fifteen  days 
before  and  ten  days  after  calving,  and  contains,  all  tolerances 
being  allowed  for,  not  less  than  twenty-five  and  five-tenths  per 

1  United   States   Department   of  Agriculture,   Food   Inspection   Decision    158 
April  2,  1915. 


184  CONDENSED  MILK  STANDARDS  AND  LAWS 

cent  (25%)   of  total  solids  and  not  less  than  seven  and  eight- 
tenths  per  cent  (7.8%)  of  milk  fat. 

Condensed  Skim  Milk. — The  original  standard  for  condensed 
skim  milk1  which  went  in  effect  January  1,  1907,  was  as  follows: 

"Condensed  skim  milk  is  skim  milk  from  which  a  consider- 
able portion  of  water  has  been  evaporated." 

Subsequently  this  standard  was  superseded  to  more  ade- 
quately control  the  manufacture  and  sale  of  condensed  skim 
milk  by%  the  following  standard2  which  became  effective  March 
31,  1917! 

Condensed  skimmed  milk,  evaporated  skimmed  milk,  con- 
centrated skimmed  milk,  is  the  product  resulting  from  the  evapo- 
ration of  a  considerable  portion  of  the  water  from  skimmed  milk, 
and  contains,  all  tolerances  being  allowed  for,  not  less  than 
twenty  per  cent  (20.0%)  of  milk  solids. 

Sweetened  condensed  skimmed  milk,  sweetened  evaporated 
skimmed  milk,  sweetened  concentrated  skimmed  milk,  is  the 
product  resulting  from  the  evaporation  of  a  considerable  portion 
of  the  water  from  skimmed  milk  to  which  sugar  (sucrose)  has 
been  added.  It  contains,  all  tolerances  being  allowed  for,  not 
less  than  twenty-eight  per  cent  (28.0%)  of  milk  solids. 

Explanatory  Notes  Concerning  the  Federal  Food  and  Drugs  Act ; 

Its  Relation  to  the  Interstate  Commerce  Law,  and  to 

the  Federal  Standards  of  Purity  for  Food  Products.3 

Any  article  of  food  entering  into  interstate  commerce  should 
conform  to  the  requirements  of  the  Federal  Law  (Pure  Food 
and  Drugs  Act). 

If  sold  other  than  in  the  original  package  in  the  state  re- 
ceived, it  should  conform  with  the  laws  of  that  state. 

The  term  "Original  Packages"  used  in  the  act  generally 
means  the  package  in  Avhich  articles  are  transported  in  interstate 
commerce,  as  distinguished  from  the  unit  packages  usually  dis- 
played on  the  shelves  of  retailers. 


1  United   States  Department  of  Agriculture,   Circular  No.   19,   1907. 

2  United   States   Department   of   Agriculture,    Food   Inspection   Decision    170, 
March  31,  1917. 

3  Hunziker,  Indiana  Agricultural  Experiment  Station  Bulletin  No.  143,  1910. 


CONDENSED  MILK  STANDARDS  AND  LAWS  185 

Section  9  of  the  act  provides  that  parties  who  make  a  guar- 
antee that  products  are  not  adulterated  or  misbranded  within  the 
meaning  of  the  Food  and  Drugs  Act,  shall  be  amenable  to  the 
prosecutions,  fines  and  other  penalties  which  would  attach  in 
due  course  to  the  dealer,  if  the  products  are  found  to  be  violative 
of  the  law. 

Under  these  provisions,  prosecutions  may  be  directed  against 
manufacturers  if  they  ship  or  deliver  for  shipment  in  interstate  or 
foreign  commerce  adulterated  or  misbranded  articles  of  food,  or 
if  they  guarantee  that  such  articles  are  not  adulterated  or  mis- 
branded,  consignees  may  be  prosecuted  if  they  sell,  in  original 
packages,  adulterated  or  misbranded  articles  of  food  which  they 
have  received  in  interstate  commerce. 

With  respect  to  the  "Standards  of  Purity  for  Food  Products" 
it  is  not  contended  that  these  standards  have  the  force  of  law. 
It  is  believed,  however,  that  they  represent  fairly  what  are  under- 
stood generally  by  reputable  manufacturers,  dealers,  and  con- 
sumers to  be  the  ingredients  of  the  products  described  therein. 
This  test  has  been  applied  by  the  courts  in  cases  tried  under  the 
Act  where  adulteration  and  misbranding  have  been  charged  of 
articles  of  food  sold  under  names  recognized  in  the  "Standards," 
but  which  were  found,  on  examination,  not  to  conform  thereto. 
It  is  apparent,  therefore,  that  the  safe  course  for  manufacturers, 
jobbers,  etc.,  engaged  in  interstate  commerce  who  wish  to  have 
their  products  free  from  exceptions  under  the  Food  and  Drugs 
Act,  is  to  see  to  it  that  they  conform  to  the  standards  described 
in  Circular  No.  19,  U.  S.  Department  of  Agriculture,  and  as 
stated  on  pages  503  to  505  of  this  bulletin.1 

REQUIREMENTS   OF   COMPOSITION   OF   CONDENSED 
MILK  FOR  WAR  CONTRACTS 

Requirements  of  condensed  milk  sold  to  the  U.  S.  Govern- 
ment.— The  composition  of  condensed  milk  and  evaporated  milk 
must  meet  the  Federal  Standards  as  specified  in  Food  Inspec- 
tion Decision  158  for  evaporated  milk  and  in  Food  Inspection 


1  These  explanations  were  secured  through  the  courtesy  of  Geo.  W.  McCabe, 
Office  of  the  Solicitor,  U.  S.  Department  of  Agriculture,  Washington,  D.  C.,  upon 
request  by  letter  in  1910.  They  equally  apply  to  the  Food  Inspection  Decisions 
which  superceeded  Circular  No.  19. 


186  COST  OF  MANUFACTURE 

Decision  170  for  sweetened  condensed  milk  and  condensed  skim 
milk. 

Requirements  of  Condensed  Milk  for  Export  to  the  Allied 
Nations. — Condensed  milk  shall  contain  not  less  than  9.2  per- 
cent butterfat. 

In  order  to  meet  the  high  butterfat  requirement  in  con- 
densed milk  furnished  to  the  Allies,  American  condenseries 
which  receive  largely  low-testing  milk  are  compelled  to  rein- 
force their  product  with  butterfat.  This  is  done  either  by 
removing  a  portion  of  the  skim  milk,  or  by  the  addition  to  the 
milk  of  butterfat  in  the  form  of  cream  or  unsalted  butter. 

CHAPTER  XXII. 
COST  OF  MANUFACTURE 

General  Discussion. — The  cost  of  manufacture  varies,  in  a 
general  way,  with  the  organization  and  size  of  the  factory, 
capacity  of  machinery  and  the  amount  of  the  output.  These 
variations  are  further  modified  by  the  cost  of  available  labor, 
the  price  of  milk,  cane  sugar,  tin  cans,  box  shooks,  coal  and 
other  supplies,  etc. 

In  a  properly  organized  plant  the  cost  of  manufacture  per 
case  of  finished  product  decreases  with  the  increase  of  the  out- 
put, provided  that  the  capaciy  of  the  machinery  is  sufficient  to 
take  care  of  such  increase.  When  the  plant  is  forced  beyond 
its  capacity,  the  factory  operates  at  a  disadvantage,  and  the 
extra  labor  and  possible  waste  and  losses  tend  to  increase  the 
cost  per  case.  When  the  output  drops  below  100  to  150  cases 
per  day.  profitable  manufacture  becomes  difficult,  the  overhead 
expense  is  out  of  proportion  with  the  business,  the  factory  can- 
not take  advantage  of  rebates  in  the  purchase  of  supplies,  the 
factory  labor  is  relatively  high,  because  skilled  men  have  to 
do  manual  labor,  and  occasional  losses  due  to  spoiled  goods 
devour  the  profits  of  a  comparatively  large  portion  of  the  entire 
output. 

The  price  of  milk  fluctuates  with  season  and  proximity  and 
strength  of  competing  markets.  The  fluctuations  embrace  a 
range  from  $1.00  to  $2.00  per  one  hundred  pounds  of  fluid  milk, 


COST  OF  MANUFACTURE  187 

or  twenty-five  cents  to  fifty  cents  per  pound  of  butter  fat. 
Maximum  war-prices  up  to  and  including  May  1918  were  $3.50 
per  100  pounds  of  milk  and  75  cents  per  pound  of  butterfat. 

Cane  sugar  varies  in  price  largely  with  the  season  and  with 
the  success  or  failure  of  the  sugar  cane  crop.  Sugar  prices 
usually  reach  their  climax  in  fall  and  their  minimum  price  in 
late  winter  or  early  spring.  The  variations  usually  fall  within 
the  limits  of  $4.00  and  $6.50  per  one  hundred  pounds  of  sugar. 
Maximum  war  price  was  7Jc  per  pound. 

Tin  cans  vary  in  price  with  style  of  can  and  whether  made 
in  the  condensery  or  bought  from  a  can-making  concern.  Some 
factories  are  paying  more  or  less  heavy  royalties  for  the  priv- 
ilege of  using  certain  patents  of  cans.  Cans  intended  to  be 
sealed  without  the  use  of  solder,  but  which  are  guaranteed  to 
make  a  hermetical  seal,  are  generally  higher  in  price  than  those 
in  the  sealing  of  which  solder  is  used.  This  difference  in  price, 
however,  is  offset,  in  part  at  least,  by  the  cost  of  the  solder 
and  gasoline.  Cans  purchased  from  can-making  concerns  usually 
are  more  expensive  than  cans  manufactured  in  the  condensery. 
This  holds  true  only  where  the  tin-shop  of  the  condensery  is 
properly  equipped  and  efficiently  manned.  The  cost  of  cans 
bought  from  can-making  concerns  is  about  fifty-five  cents  per 
case,  varying  somewhat  with  size  and  style  of  can;  when  made 
in  the  condensery  the  price  may  be  lowered  from  10  to  20  per 
cent.  Maximum  war  price  was  90  cents  per  case. 

The  cost  of  coal  varies  with  quality  and  locality.  Under 
average  conditions,  the  condensing  and  packing  of  one  pound 
of  fluid  milk  requires  about  three-tenths  of  a  pound  of  coal  or 
thirty  to  forty  pounds  per  case.  A  good  quality  of  "mine  run" 
can  be  laid  down  at  the  factory  in  states  near  the  coal  region, 
like  Indiana  and  Illinois  for  about  $2.50  per  ton,  or  in  northern 
states,  like  Wisconsin,  for  about  $3.30  per  ton.  The  cost  of  coal 
per  case,  therefore,  may  vary  from  about  three  and  eight-tenths 
to  six  and  a  half  cents  per  case.  Where  natural  gas  or  refuse 
from  lumber  mills  are  available,  the  cost  of  fuel  may  be  reduced 
materially  by  the  use  of  these  substitutes  for  coal.  Maximum 
war  price  raised  the  cost  of  coal  about  12c  per  case. 

Solder  and  gasoline  for  sealing  the  cans  average  about  three 
and  a  half  cents  per  case.  The  price  of  solder  is  about  twenty- 


188  COST  OF  MANUFACTURE 

seven  cents  per  pound  and  the  solder  used  per  case  of  forty- 
eight  cans,  amounts  to  about  one-tenth  of  a  pound.  Maximum 
war  price  raised  it  to  about  7c  per  case. 

For  venthole  cans  the  amount  of  solder  needed  is  from  .3 
to  .5  of  one  ounce  per  case. 

The  labels  vary  in  price  according  to  quality  of  paper,  and 
elaborateness  of  printing.  The  average  cost  of  labels  is  about 
four  cents  per  case.  Maximum  war  price  about  8  cents  per  case. 

The  box  shooks  and  nails  per  case  cost  about  eight  to  ten 
cents.  Maximum  war  price  raised  this  item  to  about  10  cents 
per  case. 

The  labor,  including  factory  labor,  the  office  personnel  and 
the  manager's  salary  is  about  twenty-five  cents  per  case,  varying 
obviously  with  the  organization  and  output  of  the  factory.  War 
conditions  practically  doubled  the  cost  of  labor,  making  it  about 
50  cents  per  case. 

The  interest  on  the  investment  and  insurance  amount  to 
about  two  and  a  half  to  three  cents  per  case.  A  factory  manu- 
facturing two  hundred  cases  of  condensed  milk  per  day  requires 
an  investment  of  about  $25,000  for  building  and  equipment  and 
about  $10,000  for  operating  capital. 

The  expense  of  freight  and  other  transportation  ranges  from 
about  five  to  twenty  cents  per  case,  according  to  distance.  It 
may  average  about  twelve  cents  per  case.  War  conditions  raised 
the  freight  to  about  15  cents  per  case. 

The  selling  expense  varies  considerably  with  the  organiza- 
tion of  the  sales  department  and  the  type  and  extent  of  advertis- 
ing done.  Under  favorable  conditions  it  may  be  held  down  to 
from  fifteen  to  thirty  cents  per  case.  If  premiums  are  awarded  the 
cost  is  about  ten  cents  extra.  The  introduction  of  new  brands 
often  incurs  an  expense  as  high  as  $1.00  per  case.  The  average 
sales  expense  may  be  consistently  placed  at  thirty  to  forty  cents 
per  case.  War  conditions  increased  the  selling  expense  for 
domestic  trade  about  50  per  cent. 

For  convenience  sake  the  cost  per  case  may  be  grouped  as 
follows : 


COST  OF  MANUFACTURE 


189 


SWEETENED   CONDENSED   MILK 

Cost  per  case  of  forty-eight  cans  containing  forty-six  and 
four  tenths  pounds  of  condensed  milk,  net. 


116  pounds  milk  @  1.50 

18.6  pounds,  using  16  Ibs.  per  100 

Ibs.  milk,  cane  sugar  @  5c 

Tin  cans 

Boxes    

Labels    

Solder   and  gasoline 

Coal    

Labor    

Interest  on  investment  and  insur- 


ance     

Freight     

Selling  expense 


Total  cost  per  case .. 


1913. 
1.74 

.93 

.45 

.075 

.04 

.035 

.045 

.25 

.03 
.12 
.30 

4.015 


*Increase  due" 

1917. 

to  war 

conditions. 

3.48 

100% 

1.35 

45% 

.90 

100% 

.10 

33^% 

.08 

100% 

.07 

100% 

.12 

150% 

.50 

100% 

.03 

No    Increase 

.15 

25% 

.45 

50% 

7.23 


80% 


EVAPORATED    MILK 

Cost  per  case  of  forty-eight  tall-size  cans  containing  fifty-four 
pounds  of  evaporated  milk,  net. 


110  pounds  milk  @  1.50 

Tin  cans    

Boxes    

Labels    

Solder   and   gasoline 

Coal    

Labor    

Interest  on  investment  and  insur- 
ance    

Freight     

Selling  expense  

Total  cost  per  case 


1913. 

1.65 
.55 
.075 
.04 
.02 
.045 
.25 

.03 
.12 
.30 

3.080 


1917. 

3.30 
.96 
.10 
.08 
.04 
.12 
.50 

.03 
.15 
.45 

5.73 


Increase  due 

to  war 
conditions. 
100% 
75% 
33^% 
100% 
100% 
150% 
100% 

No    Increase 

25% 
50% 


*  The  figures  showing  per  cent  increase  due  to  war  condition  were  com- 
piled by  Professor  A.  C.  Anderson,  Mich.  Agr.  College,  who  conducted  an  exten- 
sive study  on  cost  of  manufacture  of  sweetened  condensed  milk. 


PART  V 

CONDENSED  MILK  DEFECTS,  THEIR  CAUSES 
AND  PREVENTIONS 

CHAPTER  XXIII. 
CLASSIFICATION  OF  DEFECTS 

If  we  recognize  in  fresh  cow's  milk  an  article  of  food,  highly 
complex  in  composition,  subject  to  many  and  complex  changes 
and  to  rapid  deterioration  unless  handled  carefully  and  skillfully, 
then  the  successful  manufacture  of  condensed  milk,  a  product 
more  complex  in  its  composition  and  exposed  to  more  diverse, 
more  varying  and,  in  most  cases,  more  unfavorable  conditions 
than  fresh  milk,  must  involve  a  knowledge  that  extends  beyond 
the  mere  mechanical  knack  of  heating,  adding  sugar,  evap- 
orating, sterilizing,  cooling,  filling,  sealing  and  packing.  • 

The  simplicity  of  the  process  tends  to  belittle  and  hide  the 
complexity  of  the  product.  Anybody  can  acquire  the  routine 
knowledge  of  condensing  milk,  but  few  can  make  a  uniformly 
good  quality  of  condensed  milk.  It,  therefore,  happens  that 
defective  condensed  milk  is  made  now  and  then  in  most,  if  not 
all  condenseries,  and  that  the  output  of  a  poor  quality  of  con- 
densed milk  is  not  necessarily  always  the  exception  but  quite 
often  the  rule. 

Many  are  the  defects  which  cause  condensed  milk  to  be 
rejected  on  the  market  and  numerous  are  the  avenues  that  may 
lead  to  the  manufacture  of  defective  milk.  The  milk  faults  may 
be  of  mechanical,  physical,  chemical,  or  bacteriological  origin,  or 
they  may  be  due  to  a  combination  of  two  or  more  of  these  forces. 
In  some  instances  the  defects  can  be  detected  in  milk  during,  or 
immediately  after  the  process,  in  which  case  they  may  be 
remedied,  or  their  recurrence  prevented.  But  more  often,  several 
weeks  may  pass  before  abnormalities  develop  and  before  the 
manufacturer  realizes  that  something  is  wrong  with  the  milk. 
In  the  meantime,  the  conditions  which  originally  produced  the 


SWEETENED  CONDENSED  MILK  DEFECTS  191 

milk  defect  may  have  so  changed,  that  it  is  exceedingly  difficult 
to  locate  the  seat  of  the  original  trouble. 

DEFECTIVE  SWEETENED  CONDENSED  MILK 

The  following  are  the  chief  and  most  common  defects  of 
sweetened  condensed  milk : 

1.  Sandy,  rough  or  gritty 

2.  Settled 

3.  Thickened  and  cheesy 

4.  Lumpy,  white  or  yellow  buttons 

5.  Blown  or  fermented 

6.  Rancid 

7.  Putrid 

8.  Brown 

9.  Metallic. 

Sandy,  Rough  or  Gritty  Sweetened  Condensed  Milk 

General  Description. — This  is  condensed  milk  in  which  a 
portion  of  the  milk  sugar  has  been  precipitated  in  the  form  of 
crystals,  the  size  of  the  crystals  depending  on  the  conditions 
causing  crystallization.  First-class  sweetened  condensed  milk 
is  smooth  and  velvety.  Such  milk  is  not  entirely  free  from  sugar 
crystals,  but  they  are  so  minute  in  size  that  they  do  not  rob  the 
condensed  milk  of  its  natural  smoothness.  In  sandy  or  gritty 
condensed  milk  the  crystals  are  very  numerous  and  large  enough 
to  grind  between  the  teeth,  similar  to  salt  crystals  in  gritty 
butter.  The  presence  of  these  crystals  is  also  noticeable  to  the 
naked  eye ;  the  milk  looks  candied. 

Causes  and  Prevention. — The  sugar  crystals  which  render 
the  condensed  milk  rough  and  sandy  consist  largely  of  milk 
sugar.  The  solubility  of  milk  sugar  is  relatively  low.  Milk 
sugar  requires  about  six  times  its  weight  of  water  at  ordinary 
temperature  for  complete  solution.  Condensed  milk  contains 
from  12.5  to  15  per  cent,  milk  sugar  and  only  about  26.5  per  cent, 
water.  The  ratio  of  milk  sugar  to  water  in  sweetened  con- 
densed milk,  therefore,  is  1:2,  while  for  complete  solution  it 
should  be  1 : 6.  The  milk  sugar  in  this  product  is  present  in  a 


192  SWEETENED  CONDENSED  MII.K 

supersaturated  solution  and  any  condition  which  favors  sugar 
crystallization  strongly  tends  to  precipitate  this  milk  sugar, 
because  there  is  more  of  it  present  in  the  milk  tiian  the  available 
water  is  capable  of  readily  keeping  in  solution.  The  chief  factor 
that  prevents  the  milk  sugar  from  precipitating  very  badly  is 
the  great  viscosity  of  the  condensed  milk.  This  is  largely  due 
to  the  caseous  matter  and  the  cane  sugar. 

Cane  Sugar  Content. — It  has  been  argued  that  the  large 
amount  of  sucrose  which  sweetened  condensed  milk  contains, 
is  the  principal  cause  of  sandy  milk  and  of  sugar  sediment  in 
the  bottom  of  the  tin  cans,  and  that  a  reduction  in  the  amount 
of  sucrose  lessens  the  tendency  of  the  sugar  to  crystallize  and 
the  milk  to  become  sandy.  This  line  of  reasoning  is  erroneous. 
The  presence,  in  water,  of  sucrose  in  solution  does  not  materially 
lessen  the  power  of  the  water  to  dissolve  milk  sugar,  provided 
that  the  sucrose  solution  is  not  a  saturated  one.  Sweetened 
condensed  milk,  contains  about  35  to  45  per  cent,  sucrose  and 
24  to  28  per  cent,  water.  Sucrose  dissolves  in  one  half  its  weight 
of  water.  The  sweetened  condensed  milk  does  not,  therefore, 
contain  a  saturated  solution  of  sucrose. 

The  chief  factors  causing  milk  sugar  crystallization  and 
sandy  condensed  milk  are :  incomplete  solution  of  the  sucrose, 
excessive  chilling  in  the  vacuum  pan,  superheating  in  the  vacuum 
pan,  improper  cooling,  excessive  stirring,  and  warming  up  too 
cold  condensed  milk  with  the  help  of  agitation. 

Incomplete  Solution  of  Sucrose. — If  the  finished  product  is 
to  be  smooth  and  free  from  sandiness,  it  is  essential  that  the 
sucrose  which  is  added  to  the  hot,  fresh  milk  be  thoroughly  dis- 
solved before  the  mixture  reaches  the  vacuum  pan.  Undissolved 
sugar  crystals  in  a  medium  as  highly  concentrated  as  sweetened 
condensed  milk  have  much  the  same  effect  in  a  physical  way,  as 
have  bacteria  in  fresh  milk  in  a  biological  way;  they  multiply 
rapidly.  Therefore,  if  all  the  sugar  added  to  the  fluid  milk  is 
not  completely  dissolved,  the  undissolved  sugar  crystals  give 
rise  to  wholesale  precipitation  of  the  milk  sug~ar  in  this  product 
after  manufacture.  Complete  solution  of  the  cane  sugar  can 
best  be  accomplished  by  heating  the  liquid,  milk  or  water,  in 
which  the  sugar  is  to  be  dissolved,  to  the  boiling  point  and  by 
boiling  the  mixture  for  several  minutes ;  or  by  placing  the  sugar 


SWEETENED  CONDENSED  MILK  DEFECTS  19,5 

on  a  large  wire  mesh  strainer  (about  eighty  meshes  to  the  inch) 
which  stretches  across  the  sugar  well  and  allows  hot  milk  to  run 
over  this  sugar  into  the  well  below.  In  this  way  the  sugar 
crystals  must  dissolve  before  they  can  reach  the  sugar  well. 

One  of  the  safest  methods  of  insuring  complete  solution  of 
the  cane  sugar  is  to  dissolve  it  in  a  separate  kettle  in  a  sufficient 
quantitiy  of  boiling  water  (preferably  distilled  water)  and  boil- 
ing the  syrup  for  five  to  fifteen  minutes.  If  the  syrup  thus  made 
is  given  a  few  minutes  rest  it  should  become  perfectly  clear; 
by  its  clearness,  the  purity  of  the  sugar  can  also  be  observed. 
If  a  scum  forms  at  the  top  it  should  be  removed ;  then  the  hot 
sugar  syrup  is  drawn  into  the  pan.  Care  should  be  taken  that 
the  milk  already  condensing  in  the  pan  has  not  become  too  con- 
centrated, otherwise  sugar  crystallization  may  set  in.  It  is  ad- 
visable to  inject  the  sugar  syrup  gradually,  rather  than  to  wait 
until  nearly  all  the  milk  is  in  the  pan. 

Excessive  Chilling  in  the  Pan. — The  cause  of  grittiness  of 
condensed  milk  may  lie  in  the  pan  itself.  Where  the  water  used 
for  condensing  is  very  cold,  and  where  one  end  of  the  spray 
pipe  in  the  condenser  is  very  close  to  the  goose  neck  of  the  pan, 
as  is  the  case  with  most  of  the  vacuum  pans  in  use,  which  are 
equipped  with  horizontal  spray  condenser  the  chilling  of  the 
vapors  and  of  the  spray  of  milk  rising  from  the  pan  is  so 
sudden,  that  sugar  crystals  are  prone  to  form  in  the  spray  and 
along  the  walls  of  the  pan.  These  crystals  either  stick  to  the 
side  of  the  pan,  or  fall  back  into  the  milk  where  they  later  multiply 
and  cause  the  milk  to  become  sugary.  Trouble  from  this  source 
can  be  avoided  by  either  raising  the  temperature  of  the  water 
that  goes  to  the  condenser  which  is,  however,  not  practical  under 
most  conditions,  or  by  closing  the  holes  in  that  portion  of  the 
spray  pipe  which  is  nearest  the  pan.  This  can  easily  be  done 
by  wrapping  a  piece  of  galvanized  iron  or  tinplate  around  the 
portion  of  the  spray  pipe  to  be  closed,  or  by  filling  the  holes 
with  solder,  or  by  replacing  the  old  spray  pipe  by  a  new  and 
shorter  one,  properly  constructed. 

Superheating  at  End  of  Batch. — Sometimes  the  manufac- 
turer is  persistently  troubled  with  the  appearance  of  crystals  in 
the  condensed  milk  of  monstrous  size,  as  large  as  rice  kernels; 
this  condition  arrives  usually  very  gradually.  During  the  first 


i94  SWIFTENED  CONDENSED  MILK  DEFECTS 

few  days  after  manufacture,  only  a  few  of  these  large  crystals 
may  appear  in  some  of  the  cans.  In  the  course  of  a  few  weeks, 
all  of  the  cans  may  contain  specimen  of  these  "rice  crystals" 
which  increase  in  number  until  the  entire  contents  of  the  cans 
are  one  mass  of  "rice  crystals,"  rendering  the  milk  unsalable. 
The  direct  causes  of  this  particular  kind  of  sugar  crystallization 
are  excessive  concentration  of  the  condensed  milk,  the  use  of 
too  much  steam  pressure  in  the  coils  and  jacket  when  condensa- 
tion is  near  completion,  delay  in  the  drawing  off  of  the  condensed 
milk  from  the  pan,  and  leaky  steam  valves  in  the  pipes  leading 
to  jacket  and  coils. 

Taward  the  end  of  the  condensing  process  the  milk  becomes 
heavy,  thick  and  syrupy,  and  boils  with  much  less  violence.  If, 
at  this  stage  of  the  process,  excessive  steam  pressure  is  used  in 
the  jacket  and  coils,  the  milk  is  superheated,  often  causing  the 
precipitation  of  "rice  crystals."  Again,  where  the  finished  con- 
densed milk  is  drawn  from  the  pan  very  slowly,  either  owing  to 
too  small  an  outlet  in  the  bottom  of  the  pan,  or  because  the  milk 
is  forced  to  run  through  a  strainer  attached  to  the  outlet,  or 
because  the  finished  condensed  milk  is  retained  in  the  pan  as 
the  result  of  an  accident,  in  all  of  these  cases  there  is  danger 
of  superheating,  and  therefore,  of  the  production  of  these  large 
crystals.  This  danger  is  especially  great,  where  the  valves  of 
the  steam  pipes  leading  to  the  jacket  and  coils  are  leaking,  as 
is  often  the  case.  The  avoidance  of  excessive  concentration  and 
the  removal  of  any  conditions  that  tend  to  expose  the  finished 
or  the  nearly  finished  condensed  milk  to  excessive  heat  will 
usually  prevent  further  trouble  of  this  sort. 

Improper  Cooling. — The  method  used  for  cooling  the  sweet- 
ened condensed  milk  after  it  leaves  the  vacuum  pan  is  another 
important  factor  determining  the  smoothness  or  grittiness  of  the 
finished  product.  The  chief  principles  involved  here  are  the 
rapidity  and  extent  of  cooling  and  the  amount  of  agitation  to 
which  the  condensed  milk  is  subjected. 

In  order  to  fully  appreciate  the  importance  of  strict  atten- 
tion to  details  in  the  cooling  process  of  sweetened  condensed 
milk,  it  should  be  understood,  that  the  formation  of  sugar  crystals 
in  concentrated  solutions  is  enhanced  by  sudden  chilling  and 
by  excessive  agitation  of  these  solutions.  The  sudden  and  irreg- 


SWEETENED  CONDENSED  MILK  DEFECTS  195 

ular  chilling  of  a  part  or  all  of  the  sweetened  condensed  milk 
in  the  cooling-  cans  is  the  result  of  the  use  of  badly  dented  cans, 
poorly  fitting  paddles,  a  warped  condition  of  the  pivots  on  which 
the  cog  wheels  in  the  bottom  of  the  cooling  vat  revolve,  too  cold 
water,  and  the  application  of  too  much  cold  water. 

The  paddles  must  scrape  all  parts  of  the  sides  of  the  cans, 
from  top  to  bottom.  This  is  possible  only  when  the  cans  are 
intact  and  their  sides  are  smooth  and  free  from  indentations. 
The  paddles  must  be  adjusted  properly  so  that  their  edges  fit 
snugly  against  the  sides  of  the  cans,  they  must  be  firmly  fastened 
to  the  cross  bars  and  forced  against  the  sides  of  the  cans  by 
springs.  In  order  that  the  cans  may  run  true  they  must  properly 
fit  into  the  rim  of  the  cog  wheels  in  the  bottom  of  the  cooling 
vat  and  the  pivots  on  which  the  cog  wheels  revolve  must  be  per- 
pendicular. If  the  pivots  are  warped,  the  cog  wheels  cannot 
run  true  and  the  cans  wobble ;  this  causes  uneven  and  incomplete 
scraping  of  the  sides  of  cans  by  the  paddles. 

The  water  in  the  cooling  vat  should  not  be  cold,  but  have 
a  temperature  of  about  90  degrees  F.  when  the  cans,  filled  with 
the  hot  condensed  milk,  are  set  into  the  vat.  The  cold  water 
should  flow  into  the  vat  slowly  and  be  evenly  distributed 
throughout  the  vat.  This  is  best  accomplished  by  the  installa- 
tion of  a  perforated  pipe  running  the  entire  length  of  the  vat. 
The  cooling  must  be  gradual. 

Excessive  Stirring. — The  cans  should  revolve  slowly.  Rapid 
revolution  causes  excessive  agitation  of  the  condensed  milk, 
which  stimulates  the  formation  of  crystals.  About  five  revolu- 
tions per  minute  is  satisfactory.  In  order  to  make  more  effective 
the  proper  scraping  of  the  cans  by  the  paddles  when  the  cans 
revolve  slowly,  it  is  advisable  to  install  two  paddles  in  each  can, 
touching  the  periphery  of  the  can  on  opposite  sides. 

When  the  milk  has  been  cooled  to  between  60  and  70  de- 
grees F.,  the  water  should  be  drawn  from  the  cooling  vat,  or 
the  cans  should  be  removed  at  once.  For  other  methods  of  cool- 
ing see  "Cooling,"  page  94. 

Warming  Up  of  Too  Cold  Condensed  Milk. — Finally,  if  the 
condensed  milk  is  cooled  to  too  low  a  temperature,  either  by 
mistake,  or  as  the  result  of  the  cans  of  cooled  milk  standing  in 


196  SW££T#NE;D  CONDENSED  MILK 

a  very  cold  room  over  night,  so  that  the  condensed  milk  is  too 
thick  to  run  through  the  filling  machine,  it  is  best  to  warm 
it  up  by  simply  allowing  it  to  stand  in  a  warm  room.  The  prac- 
tice of  setting  the  cans  back  into  the  cooling  tank  and  revolving 
them  in  warm  water  is  objectionable,  since  this  stirring  of  the 
milk,  while  it  is  warming,  seems  invariably  to  produce  whole- 
sale sugar  crystallization,  and  therefore,  causes  the  condensed 
milk  to  become  very  gritty.  (See  also  Settled  Condensed  Milk). 

Settled  Sweetened  Condensed  Milk. 

General  Description. — By  the  term  "settled  milk"  the  con- 
densed milk  man  refers  to  condensed  milk  which  has  precip- 
itated and  thrown  down  a  portion  of  its  sugar,  forming  a  deposit 
of  sugar  crystals  in  the  bottom  of  the  can  or  barrel.  This 
deposit  may  vary  in  amount  from  a  very  thin  layer  to  a  layer  an 
inch  deep  or  more,  according  to  the  character  and  age  of  the  milk. 
The  nature  of  this  sediment  also  differs  in  different  cases  of 
settled  milk.  It  may  be  soft,  and  upon  stirring  may  mix  in  and 
dissolve  readily,  or  it  may  be  very  dry  and  hard,  in  which  case  it 
sticks  to  the  bottom  of  the  can  with  great  tenacity,  and  can  be 
removed  and  mixed  into  the  milk  with  difficulty  only.  Like 
gritty  milk,  settled  milk  is  a  very  common  condensed  milk  defect. 
Though  it  does  not  render  the  product  less  wholesome,  it  is  an 
undesirable  characteristic.  Such  milk  is  usually  rejected  on  the 
market  and  results  in  a  partial  loss  to  the  manufacturer. 

Causes  and  Prevention. — It  is  obvious,  for  reasons  above 
referred  to,  that  the  conditions  leading  up  to  the  production  of 
settled  milk,  are  closely  related  to  those  that  cause  milk  to 
become  gritty.  Condensed  milk  cannot  drop  its  milk  sugar, 
unless  the  latter  is  present  in  the  form  of  crystals.  The  absence 
of  crystals  then',  means  that  condensed  milk  will  not  settle ;  but 
experience  has  shown  that  it  is  a  practical  impossibility  to  manu- 
facture sweetened  condensed  milk  which  contains  no  sugar 
crystals  Sugar  crystals  are  always  present  in  it,  and  the  fact 
that  the  milk  is  not  sandy  or  gritty,  does  not  necessarily  mean 
that  it  will  not  settle.  Nevertheless,  the  removal  of  conditions  con- 
ducive of  sandy  or  gritty  milk,  diminishes  the  tendency  of  the 
formation  of  sugar  sediment.  The  succesful  and  uniform  pro- 
duction of  condensed  milk  that  does  not  settle,  however,  involves 


CONDENSED  MILK  DEFECTS  197 

additional    conditions    that    are    not    controlled    by   the    factors 
causing  gritty  milk. 

Effect  of  Density  on  Sugar  Sediment. — One  of  the  chief  of 
these  conditions  is  the  density  of  the  condensed  milk.  The  thin- 
ner the  condensed  milk,  the  greater  the  difference  between  the 
specific  gravity  of  the  liquid  portion  and  that  of  the  sugar  crys- 
tals; therefore,  the  more  readily  will  the  crystals  sink  to  the 
bottom.  The  viscosity  of  thin  condensed  milk,  also,  is  less  than 
that  of  thick  milk,  offering  less  resistance  to  the  force  of  gravity 
of  the  crystals.  In  the  manufacture  of  sweetened  condensed 
milk  that  has  the  proper  density,  about  2.5  to  2.8  parts  of  fresh 
milk  are  condensed  into  one  part  of  condensed  milk.  If  the 
evaporation  is  stopped  sooner,  so  that  the  ratio  is  much  less  than 
2.5  to  1,  the  condensed  milk  is  usually  too  thin  to  hold  its  sugar 
crystals  in  suspension. 

Effect  of  Fat  Content  on  Sugar  Sediment. — The  per  cent,  of 
fat  in  milk,  also,  influences  the  specific  gravity  of  the  condensed 
milk,  and  therefore,  has  some  effect  on  the  settling  of  the  sugar 
crystals,  although  to  a  relatively  slight  degree.  Nevertheless, 
sweetened  condensed  skimmed  milk  will  settle  less  readily  than 
sweetened  condensed  whole  milk. 

Effect  of  Cane  Sugar  Content  on  Sugar  Sediment. — The  per 
cent,  of  cane  sugar  materially  influences  the  specific  gravity  and 
viscosity  of  the  condensed  milk.  Milk  with  a  high  per  cent,  of 
sucrose  is  heavier,  more  viscous  and  drops  its  sugar  crystals 
less  rapidly  than  milk  with  a  low  per  cent,  of  sucrose. 

Turning  the  Cans  to  Prevent  Sugar  Sediment. — Concerns 
who  have  been  continually  troubled  with  settled  milk  often 
resort  to  the  practice  of  turning  their  cases  daily,  or  at  other 
regular  intervals.  This  keeps  the  precipitated  crystals  in  mo- 
tion, but  it  does  not  prevent  the  settling  entirely.  Moreover, 
milk  destined  to  settle,  as  the  result  of  defects  in  the  process, 
cannot  be  prevented  from  dropping  its  crystals  after  it  leaves 
the  factory.  Some  concerns  have  stooped  to  printing  on  their 
labels  statements  similar  to  the  following:  "A  sediment  in 
the  bottom  of  this  can  indicates  that  this  condensed  milk  is 
absolutely  pure  and  free  from  harmful  ingredients."  Advice  of 


198  SWEETENED  CONDENSED  MILK  DEFECTS 

the  above  denomination  is  obviously  ridiculous  as  well  as  un- 
true. 

Adding  Powdered  Milk  Sugar. — It  has  been  explained  that 
after  the  condensed  milk  is  cooled  it  contains  sugar  crystals.  If 
those  crystals  are  large,  their  cubic  content  is  relatively  great 
in  proportion  to  their  surface.  Their  buoyancy  is,  therefore, 
sufficient  to  overcome  the  resistance  of  the  surrounding  liquid 
and  they  will  drop  to  the  bottom,  forming  a  sediment.  If  these 
crystals  are  very  small  and  fine  they  are  not  objectionable  and 
they  usually  do  not  cause  settled  milk,  because  their  gravity 
force  is  insufficient  to  overcome  the  resistance  of  the  viscous 
syrup.  It  has  been  further  shown  that  the  size  of  the  sugar 
crystals  is  largely  determined  by  the  size  of  the  first  crystals 
present.  Experience  has  demonstrated  that  the  addition  to  the 
condensed  milk  before  cooling,  of  very  fine  sugar  crystals,  such 
as  powdered  milk  sugar  contains,  encourages  the  formation  of 
very  small  crystals  and  tends  to  guard  against  the  development 
of  large  and  coarse  crystals  during  subsequent  cooling.  Hence 
sugar  sediment  may  be  greatly  minimized,  if  not  entirely  pre- 
vented, by  adding  to  the  hot  sweetened  condensed  milk,  a  small 
amount  of  powdered  milk  sugar,  add  at  the  rate  of  a  teaspoon 
full  of  milk  sugar  per  one  hundred  pounds  of  condensed  milk. 
The  milk  sugar  must  be  added  as  soon  as  the  condensed  milk 
comes  from  the  pan,  if  the  milk  is  allowed  to  cool  before  the 
milk  sugar  is  added,  its  effectiveness  is  largely  lost. 

In  order  to  insure  the  full  desired  action  of  the  added  pow- 
dered milk  sugar,  this  powder  must  be  transferred  to  the  con- 
densed milk  in  such  a  manner  as  to  prevent  its  formation  into 
lumps.  It  must  be  evenly  and  finely  distributed  over  and  in  the 
condensed  milk.  The  use  of  a  flower  sifter  has  been  found  most 
suitable  for  this  purpose. 

Thickened  and  Cheesy  Sweetened  Condensed  Milk 

General  Description. — The  term  "thickened  and  cheesy" 
condensed  milk  applies  to  condensed  milk  that  thas  become 
thick  and  in  some  cases  solid.  This  is  a  very  common  trouble 
with  miflt  manufactured  in  late  spring  and  early  summer.  The 
milk  thickens  soon  after  its  manufacture  and  continues  thicken- 
ing until  it  assumes  the  consistency  of  soft  cheese,  without  the 


SWEETENED  CONDENSED  MILK  DEFECTS  199 

development  of  acid.  In  this  condition  it  usually  has  a  peculiar 
stale  and  cheesy  flavor,  disagreeable  to  the  palate.  Such  milk  is  in- 
variably rejected  on  the  market. 

Causes  and  Prevention :   Effect  of  Colostrum  on  Thickening. 

— It  has  been  suggested  that  this  spontaneous  thickening  is  due 
to  the  presence  in  the  fresh  milk  of  colostrum  milk,  because  this 
defect  appears  at  a  time  when  the  majority  of  the  cows  supply- 
ing the  condensery  freshen.  This  explanation  can  hardly  be 
considered  correct  and  there  is  no  experimental  evidence  avail- 
able substantiating  it.  If  the  presence  of  colostrum  milk  were 
the  cause  of  it,  the  thickening  would  take  place  during  the 
process,  as  the  result  of  the  action  of  heat  on  the  albuminoids. 
This  is  not  the  case.  This  thickening  begins  some  days  and 
often  some  weeks  after  manufacture  and  increases  as  the  milk 
grows  older. 

Effect  of  Cow's  Feed  on  Thickening. — Again,  the  cause  of 
this  defect  has  been  attributed  to  the  change  in  feed,  the  cows 
being  turned  from  dry  to  succulent  feed  at  the  time  when  this 
tendency  of  the  condensed  milk  to  thicken  occurs.  There  is 
no  reliable  evidence,  however,  of  how  the  succulent  pasture 
grasses  on  which  the  cows  feed  can  bring  about  this  thickening 
action  in  the  condensed  milk. 

Effect  of  Bacteria  on  Thickening. — A  third  and  far  more  rea- 
sonable explanation  is  that  this  thickening  is  the  result  of  a 
fermentation  process.  It  is  quite  probable  that  the  thickening 
of  swreetened  condensed  milk  is  closely  related  to  the  sweet- 
curdling  fermentation  in  fresh  milk.  The  sweet-curdling  of 
fresh  milk  is  a  fermentation  characteristic  of,  and  frequent  dur- 
ing late  spring  and  summer.  It  is  caused  by  certain  species  of 
bacteria  which  are  capable  of  producing  a  rennet-like  enzyme, 
which  has  the  power  to  curdle  milk  in  the  sweet  state.  These 
bacteria  are  known  to  be  closely  associated  with  dirt  and  filth, 
especially  from  the  feces,  and  gain  access  to  the  milk  usually 
on  the  farms  where  the  production  and  handling  of  milk  is  not 
accomplished  under  most  sanitary  conditions. 

It  is  further  known,  as  the  result  of  analyses  that,  in  spite 
of  the  large  per  cent,  of  cane  sugar  which  sweetened  condensed 
milk  contains,  the  bacteria  in  it  increase  with  the  age  of  the 


200  SWEETENED  CONDENSED  MILK  DEFECTS 

milk.  The  thickening  of  the  sweetened  condensed  milk  in  early 
summer,  therefore,  very  probably  is  the  result  of  a  slow  curdling 
of  its  casein,  caused  by  enzymes  which  are  produced  by  bacteria. 
It  has  further  been  demonstrated  that  condensed  skim  milk 
thickens  more  readily  than  condensed  whole  milk,  which  may  be 
explained  by  the  fact  that  condensed  milk  without  butter  fat 
represents  a  more  favorable  medium  for  bacterial  growth.  Fur- 
thermore, it  has  been  conclusively  demonstrated  by  the  writer 
and  others  that  the  addition  of  cane  sugar  to  condensed  milk,  in 
excess  of  that  present  in  normal  condensed  milk,  greatly  retards 
thickening.  This  fact  suggests  that  the  higher  per  cent,  of 
sucrose  has  an  inhibiting  effect  on  the  enzyme-producing  bac- 
teria, and  perhaps,  on  the  action  of  the  enzyme  itself.  This 
condensed  milk  defect  can  be  prevented  entirely  by  using,  during 
the  summer  months,  eighteen  pounds  of  sucrose  per  one  hundred 
pounds  of  fresh  milk,  so  that  the  condensed  milk  contains  about 
45  per  cent,  sucrose. 

Effect  of  Finishing  in  Pan  With  High  Steam  Pressure  on 
Thickening. — Abnormally  thick  condensed  milk  is  also  the  result 
of  overheating  the  condensed  milk  in  the  vacuum  pan  toward 
the  close  of  the  process.  The  batch  should  be  finished  with  low 
steam  pressure  in  the  jacket  and  coils,  not  to  exceed  five  pounds 
of  pressure,  and  the  milk  should  be  drawn  from  the  pan  at  once 
after  condensation  is  completed.  The  superheating  to  which 
the  condensed  milk  is  subjected  in  the  pan,  when  finishing  with 
a  high  steam  pressure  in  jacket  and  coils,  or  when  the  milk  is 
not  drawn  from  the  pan  promptly  when  the  vacuum  pump  is 
stopped,  or  when  an  effort  is  made  to  condense  to  a  very  high 
degree  of  concentration,  is  almost  sure  to  cause  the  finished 
product  to  spontaneously  thicken  with  age  and  this  tendency 
is  especially  pronounced  in  the  spring  and  early  summer. 

Effect  of  Age  on  Thickening. — Finally,  all  sweetened  con- 
densed milk  has  a  tendency  to  thicken  with  age.  Kxposure  to 
high  storage  temperature  (summer  heat)  hastens  this  action. 
The  rapidity  of  thickening  in  storage  increases  with  the  increase 
in  temperature.  This  tendency  is  very  much  reduced,  therefore, 
by  protecting  the  goods  from  high  temperatures  and  by  storing 
them  below  60  degrees  F.  (See  Chapter  on  "Storage,"  page  152.) 


SWEETENED  CONDENSED  MII.K  DEFECTS  201 

Lumpy  Sweetened  Condensed  Milk 

General  Description. — Lumps  of  varying  denominations  are 
not  infrequently  found  in  sweetened  condensed  milk.  They  may 
be  soft  and  permeate  the  contents  of  the  can  throughout,  or  may 
appear  especially  in  the  form  of  a  "smear"  along  the  seams  of 
the  can ;  or  again,  they  may  float  on  the  surface,  in  which  case 
they  are  usually  hard  and  cheesy,  and  either  white  or  yellow  in 
color.  Their  presence  gives  the  contents  of  the  can  an  unsightly 
appearance  at  best,  and  in  many  cases,  they  spoil  its  flavor. 
They  naturally  suggest  to  the  consumer  that  something  is  wrong 
with  the  condensed  milk,  and  cause  him  to  reject  the  whole 
package. 

Causes  and  Prevention. — The  chief  causes  of  lumpy  con- 
densed milk  are :  poor  quality  of  fresh  milk,  unclean  pipes  in  fac- 
tory, milk  from  fresh  cows,  acid  flux  in  tin  cans,  and  unclean 
and  contaminated  tin  cans. 

Poor  Quality  of  Fresh  Milk  and  Unclean  Factory  Conditions. 

— Upon  opening  the  can  of  condensed  milk,  even  shortly  after  it 
is  filled,  the  lid  is  covered  with  large  and  small  lumps  and  specks 
sticking  to  the  tin,  presenting  a  very  uninviting  appearance. 
This  condition  can  usually  be  traced  back  to  a  poor  quality  of 
fresh  milk,  containing  too  much  acid.  Very  often,  too,  the  cause 
lies  in  the  factory  itself,  where  it  is  due  to  lack  of  cleanliness. 
A  thorough  inspection  of  milk  pipes  and  pumps  generally  shows 
accumulations  of  remnants  of  milk  which  get  into  the  milk  of 
the  succeeding  batch.  Where  this  condition  exists,  it  is  notice- 
able that  the  first  batch  of  the  day  contains  more  specks  and 
lumps  than  the  succeeding  ones.  These  lumps  do  not,  as  a  rule, 
grow  larger  in  size  nor  increase  in  number  with  the  age  of  the 
condensed  milk,  but  they  injure  its  appearance  to  the  eye,  and 
certainly  cannot  add  to  the  wholesomeness  of  the  milk.  They 
might  easily  become  the  cause  of  the  formation  of  ptomains. 
A  more  rigid  inspection  of  all  the  fresh  milk  as  it  arrives  at  the 
factory  and  thorough  scouring  of  all  milk  tanks  and  milk  pumps, 
pipes  and  conveyors  usually  prevents  the  recurrence  of  this 
defect. 

Milk  from  Fresh  Cows. — During  early  spring  there  is  a 
strong  tendency  of  the  jacket  and  coils  in  the  vacuum  pan  to 


202  SWIFTENED  CONDENSED  MILK 

become  coated  with  a  thick  layer  of  gelatinous  and  lumpy  milk. 
This  is  probably  due  to  the  fact  that  milk  during  these  months 
comes  largely  from  freshened  cows  and  may  contain  some  colos- 
trum milk  which  coagulates  when  subjected  to  heat,  or  that 
the  proteids  of  milk  from  these  fresh  cows  are  abnormally 
sensitive  to  heat.  This  thickened  material  usually  does  not  leave 
the  pan  until  most  of  the  condensed  milk  has  been  drawn  off. 
It,  therefore,  appears  in  the  last  one  or  two  cooling  cans.  If 
the  milk  in  these  cans  is  mixed  with  the  rest  of  the  condensed 
milk,  the  lumps  will  appear  again  in  the  tin  cans.  The  last  cans 
drawn  from  the  pan  should,  therefore,  be  kept  separate.  The 
contents  of  these  remnant  cans  may  be  redissolved  in  hot  water 
and  should  be  recondensed  in  a  succeeding  batch.  In  this  way 
the  manufacturer  sustains  practically  no  loss.  In  order  to  pre- 
vent these  lumps  from  getting  into  the  cooling  cans,  some  fac- 
tories attach  a  strainer  to  the  outlet  of  the  pan.  This  practice 
is  as  unneccessary,  as  it  is  damaging  to  the  milk  in  the  pan. 
The  straining  greatly  retards  the  removal  of  the  milk  from  the 
pan,  and  the  milk  is  held  in  the  hot  pan  so  long,  as  to  cause 
partial  superheating  which  is  otherwise  detrimental  to  its  quality. 

Comparative  Composition  of  Gelatinous  Coating  of  the  Jacket 

and  Coils  and  of  Normal  Condensed  Milk  of  the  Same 

Batch,  made  April  23,  1908 

Coating  of  jacket  Normal  condensed 

and  coils  milk 

Moisture                            24.76  per  cent.  30.34  per  cent. 

Lactose                               13.12         "  13.16 

Fat                                      9.50        "  7.44 

Curd                                   8.14        "  7.30 

Ash                                       1.42  1.80 

Acid                                       .33        "  .40 

Sucrose                               41.36  40.02 

98.63  per  cent.  100.46  per  cent. 

The  above  analyses  were  made  in  order  to  determine  the 
difference  in  chemical  composition  between  that  part  of  the  batch 


SWEETENED  CONDENSED  MIUC  DEFECTS  203 

which,  in  the  spring  of  the  year,  forms  a  gelatinous  coating  on 
the  jacket  and  coils  and  that  part  which  remains  normal.  The 
figures  do  not  show  as  great  a  difference,  as  the  physical  com- 
parison of  the  two  products  would  suggest.  Possibly  the  most 
significant  point  these  analyses  show  is  that,  while  the  proteids 
in  the  coating  are  higher,  the  ash  is  lower  than  in  the  normal 
condensed  milk. 

A  large  portion  of  the  ash  of  milk  is  present  in  chemical 
combination  with  the  casein,  which  does  not  curdle  by  heat, 
while  the  albumin,  which  is  coagulated  by  heat,  contains  only 
a  very  small  amount  of  ash.  Therefore,  the  fact  that  an  increase 
in  the  proteids  of  this  gelatinous  coating  is  accompanied  by  a 
decrease  in  the  ash  content,  would  suggest  that  the  proteids  of 
the  coating  of  the  jacket  and  coils  consist  of  more  albumin  and 
less  casein  than  the  proteids  of  the  normal  condensed  milk  of 
the  same  batch.  Since  this  coating  of  the  jacket  and  coils  occurs 
only  in  the  spring  of  the  year,  when  most  of  the  cows  freshen, 
it  is  reasonable  to  assume  that  this  coating  is  the  result  of  the 
acceptance  at  the  factory  of  milk  too  soon  after  calving  and 
which  contains  excessive  quantities  of  proteids  and  other  sub- 
stances which  are  highly  sensitive  to  heat,  such  as  albumin, 
colostrum,  etc. 

Excess  of  Acid  in  Condensed  Milk  and  Acid  Flux  in  Tin 
Cans. — The  presence  in  the  condensed  milk  of  organic  and 
mineral  acids,  in  excess  of  the  amount  which  normal  fresh  milk 
contains,  is  conducive  of  the  formation  of  lumps. 

Excessive  amounts  of  acid  in  condensed  milk  may  be  the 
result  of  fermentations,  usually  due  to  a  poor  quality  of  sugar, 
or  of  the  use  of  acid  flux  in  the  making  and  sealing  of  the  tin 
cans.  Condensed  milk  that  shows  acid  or  gaseous  fermentation 
usually  contains  lumps.  The  acid  which  it  develops  as  the  result 
of  the  fermentation,  curdles  the  casein  with  which  it  comes  in 
contact. 

One  of  the  most  common  channels  through  which  condensed 
milk  may  become  contaminated  with  acid  mechanically,  is  the 
use  of  cans,  in  the  manufacture  and  sealing  of  which  acid  flux  was 
used.  The  acid  flux  generally  used  contains  zinc  chloride.  The  flux 
precedes  the  solder  and  some  of  it  is  bound  to  sweat  through  the 


204  SWEETENED  CONDENSED  MII^K 

seams  into  the  interior  of  the  cans.  Zinc  chloride  is  a  highly  poi- 
sonous product  and  its  use  in  the  manufacture  of  tin  cans,  which 
are  intended  for  receptacles  of  human  food,  should  be  prohibited 
by  law.  Aside  from  its  injurious  effect  on  the  health  and  life  of  the 
consumer,  its  presence,  even  in  small  quantities  in  condensed 
milk,  is  a  detriment  to  its  market  value.  In  such  cans  there 
accumulate,  usually  along  the  seams,  lumps  and  smeary  sub- 
stances which  have  been  found  to  consist  of  casinate  of  zinc. 

Most  commercial  soldering  fluxes  consist  largely  of  zinc 
chloride  and  are  highly  acid,  although  many  of  these  are  adver- 
tised as  acid-free  fluxes.  In  order  to  avoid  condensed  milk  con- 
taining lumps  from  this  source,  cans  should  be  used,  in  the 
manufacture  of  which  a  strictly  acid-free  flux  is  used  and  which 
are  sealed  with  acid-free  flux.  Dry,  powdered  resin  or  resin 
dissolved  in  alcohol  or  gasoline  are  harmless  in  this  respect  and 
are  just  as  effective  fluxes,  as  acid  flux. 

Unclean  and  Contaminated  Tin  Cans. — Finally,  there  fre- 
quently appear  in  sweetened  condensed  milk,  species  of  lumps 
which  are  firm  and  cheesy  and  which  usually  float  on  top  of  the 
milk  in  the  can.  These  are  called  buttons.  Some  are  white, 
others  are  yellow.  These  buttons  appear  in  old  milk  more  fre- 
quently than  in  milk  that  has  been  in  storage  for  a  short  time 
only.  They  grow  in  size  and  sometimes  one  "button"  covers 
the  entire  surface  of  the  condensed  milk  in  the  can.  Their  origin 
is  not  well  understood,  but  they  are  supposed  to  be  the  result 
of  fungus  growth.  It  is  not  improbable  that  they  are  produced 
by  molds,  the  spores  of  which  gain  access  to  the  condensed  milk 
in  the  factory,  or  to  the  cans  before  they  are  filled.  These  "but- 
tons" appear  in  the  canned  goods  and  in  the  barrel  goods.  Their 
occurrence  can  be  minimized  by  protecting  the  condensed  milk 
and  the  empty  cans  from  dust  and  other  impurities,  by  steriliz- 
ing the  cans  immediately  before  use,  and  by  paraffining  and 
thoroughly  steaming  the  barrels  before  filling. 

Blown,  or  Fermented  Sweetened  Condensed  Milk 

General  Description. — One  of  the  most  disastrous  troubles 
in  the  manufacture  of  sweetened  condensed  milk  is  the  appear- 
ance of  "swell  heads."  This  term  is  applied  to  cans  of  condensed 


SWEETENED  CONDENSED  MILK  DEFECTS  205 

milk,  the  contents  of  which  have  undergone  gaseous  fermenta- 
tion, the  resulting  pressure  causing  the  ends  of  the  cans  to  bulge 
or  swell,  and  frequently  to  burst  open  the  seams.  In  the  case 
of  barrel  goods,  the  pressure  may  cause  the  barrel  head  to  blow 
out.  This  gaseous  fermentation  is  usually,  though  not  always, 
accompanied  by  the  development  of  acid  and  the  formation  of 
lumps. 

This  fermented  milk  is  worthless  for  any  purpose  and  means 
a  total  loss  to  the  manufacturer.  The  loss  is  generally  aug- 
mented by  the  fact  that  this  trouble  does  not  become  noticeable 
at  once;  its  development  requires  several  weeks,  so  that  large 
quantities  of  condensed  milk  may  have  been  manufactured  before 
it  is  apparent  that  the  milk  is  defective.  Some  of  the  goods  may 
have  reached  the  market  before  the  cans  begin  to  swell,  in  which 
case  the  reputation  of  the  respective  brand  is  jeopardized.  In 
some  instances  entire  batches  show  this  defect,  while  in  others 
only  a  few  cans  or  cases  of  each  batch  are  blown. 

Causes  and  Prevention. — This  defect  may  be  brought  about 
through  various  channels.  In  most  cases  it  is  due  to  contamina- 
tion of  the  milk,  on  the  farm  or  in  the  factory,  with  specific 
micro-organisms  which  are  capable  of  fermenting  one  or  more 
of  its  ingredients,  in  spite  of  the  preservative  action  of  the 
sucrose;  or  the  condensed  milk  may  contain  highly  fermentable 
substances  such  as  glucose  or  invert  sugar,  so  that  the  germs 
normally  present  in  the  condensed  milk  become  active  and  pro- 
duce gas ;  or  the  milk  may  not  be  condensed  to  a  sufficient  degree 
of  concentration,  or  may  not  contain  adequate  quantities  of 
sucrose,  to  render  it  immune  to  the  bacteria  normally  present. 
The  cans  may  also  bulge  without  bacterial  action,  as  the  result 
of  exposure  to  a  wride  range  of  temperatures,  causing  mechanical 
contraction  and  expansion  of  the  contents. 

Contamination  With  Specific,  Gas-Producing  Bacteria  and 
Yeast. — This  is  by  far  the  most  common  cause  of  blown  milk. 
While  the. micro-organisms  which,  under  normally  sanitary  pro- 
duction of  milk  and  factory  conditions,  gain  access  to  the  con- 
densed mik,  are  largely  inhibited  and  do  not  ferment  the  sweet- 
ened condensed  milk,  there  are  certain  specific  forms  of  bacteria 
and  yeast  whose  growth  is  not  retarded  by  the  concentrated 


206  SWEETENED  CONDENSED  MILK 

sugar  solution  of  this  product.  Contamination  of  the  condensed 
milk  with  these  specific  organisms  is  usually  the  result  of  highly 
unsanitary  conditions  in  the  handling  of  the  condensed  milk. 

The  products  of  fermentation  depend  on  the  particular  type 
and  species  of  micro-organisms  involved.  In  most  cases  the 
sucrose  is  the  chief  constituent  attacked,  but  the  lactose,  also, 
is  capable  of  gaseous  fermentation,  though  instances  of  lactose 
fermentation  in  sweetened  condensed  milk  are  not  common. 

The  gaseous  fermentation,  of  lactose  is  largely  caused  by 
bacteria,  yeast  and  molds  which  contain  the  lactose-splitting 
enzyme  "lactase,"  which  has  the  power  of  hydrolyzing  the  lac- 
tose. While  the  species  of  organisms  which  cause  lactic  acid 
fermentation  from  lactose  are  very  numerous,  those  containing 
the  enzyme  lactase  and  thereby  causing  gaseous  fermentation 
from  lactose,  are  less  frequent,  at  least,  as  far  as  their  access  to 
milk  and  condensed  milk  is  concerned.  It  is  generally  under- 
stood, though  not  experimentally  proven,  that  species  of  micro- 
organisms which  do  not  contain  the  enzyme  lactase  have  no  gas- 
producing  action  on  lactose. 

The  great  majority  of  cases  of  gaseous  fermentation  of 
sweetened  condensed  milk  are  the  result  of  the  action  of  micro- 
organisms on  the  sucrose,  especially  tho>se  which  contain  the 
enzyme  "invertase."  The  majority  of  yeasts  secrete  invertase 
and  ferment  sucrose,  producing  alcohol  and  carbon  dioxide  to 
the  same  extent  as  in  the  case  of  glucose  fermentations.  The 
process  is  considerably  slower,  however,  especially  at  the  start, 
owing  to  the  fact  that  inversion  of  the  sucrose  must  precede 
fermentation.  For  this  reason  gaseous  fermentations  of  sweet- 
ened condensed  milk  do  not  become  noticeable  until  the  product 
is  one  or  several  weeks  old. 

Contamination  With  Yeast  on  the  Farm. — In  most  cases  of 
yeast  fermentations  of  sweetened  condensed  milk,  the  source  of 
contamination  lies  in  the  factory.  While  such  contamination 
may  and  often  does  occur  on  the  farm,  the  yeast  cells,  though 
they  may  be  spore-bearing,  are  destroyed  by  the  heat  to  which 
the  fresh  milk  is  subjected  in  the  forewarmers  and  before  it 
reaches  the  vacuum  pan.  The  thermal  death  point  of  all  forms 
of  yeast  which  have  come  to  the  attention  of  the  writer  in  con- 


CONDENSED    MlLK    DEFECTS  207 

nection  with  a  vast  number  of  investigations  of  fermented  con- 
densed milk  was  below  180  degrees  F.  If  all  the  milk  is  properly 
heated  in  the  forewarmers  to  190  degrees  F.  or  over,  there  is, 
therefore,  little  danger  of  fermented  milk,  caused  by  contamina- 
tion of  the  fresh  milk  on  the  farm  with  yeast.  If,  however,  the 
heating  is  incomplete,  or  if  some  of  the  milk  passes  into  the 
vacuum  pan  without  having  been  properly  heated,  there  is  danger 
of  milk,  contaminated  with  these  yeasts,  to  result  in  fermented 
condensed  milk. 

Contamination  with  Yeast  in  the  Factory. — As  previously 
stated,  yeast  fermentation  of  condensed  milk  can  almost  in- 
variably be  traced  back  to  contamination  in  the  factory.  After 
the  milk  leaves  the  forewarmers,  or  hot  wells,  it  is  never  again 
heated  to  temperatures  high  enough  to  destroy  these  destructive 
yeast  cells.  The  channels  through  which  yeast  contamination 
may  occur  in  the  factory  are  many. 

Contaminated  Sugar. — The  sucrose  itself  may  be  contam- 
inated with  yeast.  This  is  frequently  the  case  and  especially  so 
if  the  sugar  is  exposed  to  dampness,  and  if  flies,  bees,  ants  or 
cockroaches  have  access  to  it. 

Again,  the  sugar  may  reach  the  milk  through  a  sugar  chute. 
The  lower  end  of  the  chute  is  usually  located  directly  over  the 
steaming  milk  in  the  hot  well.  The  vapors  arising  from  below 
may  be  condensed  in  the  chute,  causing  its  inside  walls  to  become 
damp,  and  sugar  Avill  adhere  to  the  damp  surface,  forming  a 
crust.  If  the  crust  is  not  removed  daily,  its  contamination  with 
yeast  and  other  dangerous  micro-organisms  is  almost  inevitable 
and  whenever  this  crust  peels  off  and  drops  into  the  milk,  the 
contamination  may  be  carried  into  the  finished  product,  giving 
rise  to  gaseous  fermentation. 

Contaminated  Machinery  and  Milk  Conveyors. — Remnants 
of  milk  may  lodge  in  the  condenser,  in  the  vacuum  pan,  in  the 
pipes  conveying  the  milk  and  condensed  milk,  in  the  cooling 
cans  or  coils,  in  the  supply  tank  of  the  filling  machine,  or  the 
filling  machine  itself.  These  remnants  are  all  subject  to  con- 
tamination and  may  become  the  source  of  fermented  condensed 
milk.  The  strictest  attention  to  scrupulous  cleanliness  and  con- 
tinuous inspection  of  all  parts  of  conveyors  and  apparatus  which 


208 


SWEETENED  CONDENSED  MILK  DEFECTS 


come  in  contact  with  the  milk  are  the  only  consistent  safeguards 
against  trouble  from  this  source. 

Contamination  Through  "Cut-opens." — It  is  customary  to 
empty  the  contents  of  sample  cans  which  are  cut  open  for  any 
purpose,  back  into  the  condensed  milk  of  suceeding  batches.  If 
these  samples  happen  to  be  contaminated  with  the  fermenting 


Fig.    54.     Gaseous    fermentation    in 
sweetened    condensed    milk 


Fig.  55.      Yeast  cells  causing 
gaseous  fermentation 

This  species  is  capable  of 
fermenting  sugar  solutions 
containing  85%  sucrose. 


germs,  the  defect  is  naturally  propagated  from  batch  to  batch 
and  it  is  exceedingly  difficult  to  locate  the  source  of  the  trouble. 
It  is  obvious  that  all  suspicious  "cut-opens"  should  be  rejected 
and  that  all  "cut-opens"  that  are  utilized  should  be  emptied  into 
the  hot  well  where  their  contents  are  boiled  up  again. 

Dangerous  Effect  of  Poor  Quality  of  Sugar. — (Sweetened 
condensed  milk  is  not  sterile.  There  is  no  part  of  the  process 
that  would  render  it  sterile  and,  from  the  time  it  leaves  the 
vacuum  pan  to  the  time  when  the  tin  cans  are  hermetically  sealed, 
it  is  exposed  to  contamination  with  microbes,  even  though  the 
factory  observes  the  most  rigid  attention  to  scrupulous  sanita- 
tion and  cleanliness.  Most  of  these  microbes  are  harmless  and 
their  growth  is  inhibited  by  the  preservative  action  of  the  cane 
sugar.  If,  however,  a  poor  quality  of  sucrose  is  used,  which  may 


SWEETENED  CONDENSED  MILK  DEFECTS  209 

contain  traces  of  invert  sugar,  or  acid,  etc.,  many  of  these  com- 
mon species  of  micro-organisms,  harmless  in  normal  condensed 
milk,  find  an  opportunity  to  develop  and  cause  gaseous  fermenta- 
tion. The  presence  of  invert  sugar  makes  unnecessary  the  action 
of  invertase  in  order  to  start  fermentation ;  thus,  microbes  which 
do  not  secrete  invertase  and  are  otherwise  harmless,  may  become 
detrimental  in  the  presence  of  invert  sugar,  added  to  the  milk 
in  the  form  of  a  poor  quality  of  cane  sugar.  In  a  similar  way 
the  use  in  condensed  milk  of  commercial  glucose,  as  a  substitute 
of  a  part  of  the  cane  sugar,  and  in  order  to  reduce  the  cost  of 
manufacture,  is  bound  to  cause  disastrous  results.  Nothing  but 
the  best  refined,  granulated  sucrose  should  be  used,  the  best  is 
the  cheapest. 

Dangerous  Effect  of  High  Acid  in  Milk. — Acids  have  the 
power  of  inverting  sucrose.  The  inversion  by  acid  is  especially 
active  in  the  presence  of  heat.  The  milk  in  the  vacuum  pan  is 
condensing  at  130  to  150  degrees  F.  These  temperatures  are 
most  favorable  to  inversion  of  a  portion  of  the  sucrose  in  the 
presence  of  acid.  The  higher  the  acid  content  of  the  milk,  the 
more  active  is  the  inversion.  Since  invert  sugar  is  the  very 
ingredient  necessary  to  cause  bacterial  action  in  the  finished 
product,  it  is  essential  that  the  acidity  of  the  milk  to  be  con- 
densed, should  be  held  down  to  the  minimum  in  order  to  avoid 
trouble  from  this  source. 

Contamination  with  Butyric  Acid  Bacteria. — Frequently  the 
troublesome  microbe  is  not  a  yeast,  but  belongs  to  a  species  of 
bacteria  highly  resistent  to  heat,  and  which  fail  to  be  destroyed 
by  heating  the  milk  to  the  boiling  point.  In  this  case,  the  con- 
tamination usually  originates  on  the  farm.  Organisms  of  this 
kind,  which  infest  the  milk  on  the  farm  in  this  connection,  largely 
belong  to  the  butyric  acid  group.  The  most  prominent  among 
them  are  Granulobacillus  saccharo-butyricus  mobilis  or  Bacillus 
saccharobutyricus,  Bacillus  esterificans,  Bacillus  dimorphobuty- 
ricus.  The  putrefactive  forms  of  butyric  acid  organisms,  such  as 
Bacillus  putrificus,  Plectridium  foetidum,  Plectridium  novum, 
etc.,  do  not  seem  to  thrive  in  sweetened  condensed  milk. 

The  contamination  may  occur  from  dust  of  hay  and  other 
fodder,  grain,  bedding,  or  the  unclean  coat  of  the  udder  and  sur- 


210  SWEETENED  CONDENSED  MILK 

rounding  portions  of  the  animal,  or  from  milking  with  wet  and 
unclean  hands,  or  from  remnants  of  milk  in  unclean  utensils. 

It  is  noticeable  that  the  great  majority  of  cases  of  blown 
milk  appear  during  late  summer  and  early  fall,  when  the  crops 
are  harvested  and  the  air  in  the  barn  is  frequently  loaded  with 
dust  from  the  incoming  crops.  Gelatin  plates  exposed  in  the 
stable  before  and  during  the  filling  of  silos  showed  an  enormous 
increase  of  colonies  on  the  plates  exposed  during  the  filling  of  the 
silos.  Milk  drawn  under  such  conditions  is  naturally  subjected 
to  excessive  contamination,  unless  special  precautions  are  ob- 
served. 

A  very  common  source  of  these  butyric  acid  organisms  also 
is  remnants  of  milk  in  pails,  strainers,  coolers,  cans  and  any 
other  utensils  with  which  the  milk  may  come  in  contact,  also 
polluted  water  used  for  rinsing  the  utensils.  The  cheese-cloth 
strainer,  owing  to  the  fact  that  it  is  difficult  to  thoroughly  clean 
and  that  it  is  very  seldom  really  clean,  is  a  very  serious  menace  in 
this  respect.  Under  average  farm  conditions,  unless  a  new  cloth 
strainer  is  used  at  each  milking,  it  is  safe  to  condemn  it  entirely 
and  to  recommend  the  use  of  a  fine  wire  mesh  strainer  containing 
about  eighty  meshes  to  the  inch.  On  some  farms  the  milk  is 
held  in  a  set  of  old  cans  which  are  kept  on  the  farm  and  which 
never  reach  the  can  washer  at  the  factory.  Just  before  hauling 
time  these  cans  are  emptied  into  the  clean  cans  from  the  factory. 
These  old  cans  are  often  not  washed  properly  and  sometimes  not 
at  all.  The  remnants  of  milk  in  these  cans  breed  these  undesir- 
able germs  and  contaminate  the  fresh  milk.  It  is  obvious  that 
such  a  practice  is  bound  to  jeopardize  the  quality  and  life  of  the 
finished  product  and  may  constitute  a  continuous  cause  of  blown 
milk. 

Effect  of  Amount  of  Sucrose. — Since  the  sucrose  contained 
in  sweetened  condensed  milk  is  the  chief  agent  preserving  it, 
it  is  obvious  that  enough  of  it  must  be  added  to  insure  adequate 
preservative  action.  Experience  has  shown  that  about  39  to  40 
per  cent,  of  sucrose  is  required  to  preserve  the  condensed  milk 
under  average  conditions.  A  higher  per  cent,  of  sucrose  would 
naturally  intensify  the  preservative  action  and  inhibit  the  growth 
of  the  bacteria  normally  present  more  completely ;  but  if  enough 
sugar  were  added  to  also  inhibit  the  growth  of  and  make  harm- 


SWEETENED  CONDENSED  MILK  DEFECTS  211 

less  those  violent  gas-producing  butyric  acid  bacteria  and  yeast 
cells,  which  thrive  in  sweetened  condensed  milk  containing  40 
per  cent,  sucrose,  the  product  would  be  objectionable  from  the 
consumer's  point  of  view.  The  logical  avoidance  of  "swell  heads" 
as  the  result  of  these  undesirable  germs,  therefore,  must  ever  lie 
in  prevention,  rather  than  cure.  The  sanitary  standard  of  pro- 
duction on  the  farm  and  of  the  process  in  the  factory  must  be 
raised  to  and  maintained  on  a  level  where  the  milk  is  protected 
from  contamination  with  these  micro-organisms. 

The  writer1  has  isolated  yeast  from  fermented  sweetened 
condensed  milk  that  produced  vigorous  gas  formation  in  media 
containing  as  high  as  85  per  cent,  sucrose  (600  grams  sucrose  in 
100  cc.  whey  bouillon). 

Effect  of  Too  Thin  Condensed  Milk.— Condensed  milk  that 
is  too  thin  is,  also,  prone  to  start  fermenting,  since  it  is  deficient 
in  the  chief  preserving  agents,  i.  e.,  density  and  per  cent,  of 
sucrose.  It  is  not  safe  to  put  goods  on  the  market,  with  a  ratio 
of  concentration  much  less  than  2.5:1. 

Effect  of  Excessively  Low  Temperatures. — The  cans  of 
sweetened  condensed  milk  may  also  bulge  in  the  case  of  cans 
with  non-hermetical  seals,  exposed  successively  to  excessive  cold 
and  to  room  temperature.  In  this  case,  the  condensed  milk  is 
entirely  normal  and  unaffected,  and  the  bulging  is  the  result 
of  mechanical  contraction  and  expansion  by  cold  and  heat.  This 
is  possible  only  where  the  seal  of  the  cans  is  not  entirely  her- 
metical.  In  the  case  of  the  Gebee  seal  with  the  burr  cap,  and 
the  McDonald  seal  with  the  friction  cap,  the  seal  is  not  absolutely 
air-tight.  While  the  pores  between  cap  and  can  are  microscopic 
in  size,  and  not  large  enough  to  permit  the  contents  from  leak- 
ing out,  they  are  sufficient  to  admit  air.  The  cans  are  usually 
filled  with  the  condensed  milk  at  a  temperature  of  about  70  de- 
grees F.  If  the  filled  and  sealed  cans  are  exposed  to  a  very 
low  temperature,  as  may  be  the  case  in  winter,  in  store  houses  or 
in  transit,  the  milk  and  the  air  in  the  cans  contract.  This  con- 
traction is  intensified  by  the  fact  that  the  sweetened  condensed 
milk  does  not  freeze.  Its  concentration  is  so  great  that  its  freez- 
ing point  is  usually  below  the  most  extreme  cold  storage  tem- 


1  Hunziker,  Results  not  published. 


212  SWEETENED  CONDENSED  MILK 

perature.  This  contraction  of  milk  and  air  in  the  cans  produces 
a  partial  vacuum,  causing  air  to  be  drawn  into  the  cans  through 
the  microscopic  openings  of  the  seal.  When  the  cans  are  sub- 
sequently moved  into  places  with  a  more  moderate  temperature, 
the  milk  and  the  air  in  the  cans  expand,  but  the  milk  on  the  in- 
side of  the  cans  forms  a  seal  preventing  the  escape  of  the  sur- 
plus air.  The  result  is  that  the  ends  of  the  cans  bulge.  This 
phenomenon  has  been  experimentally  determined  by  the  author1 
While  the  contents  of  such  cans  are  perfectly  normal,  the  package 
suggests  fermented  milk  and  may  be  rejected  on  the  market. 

It  is  evident,  from  the  above  data,  that  the  swelling  of  the 
cans,  as  the  result  of  exposure  to  excessively  low  temperatures, 
can  readily  be  avoided,  either  by  protecting  the  cans  against  ex- 
cessive cold,  or  by  using  cans  that  are  sealed  with  solder.  The 
solder-seals  are  hermetical  so  that  no  air  can  be  drawn  into  the 
cans  when  a  partial  vacuum  is  formed  in  their  interior  as  the 
result  of  the  contraction  of  air  and  milk. 

Rancid  Sweetened  Condensed  Milk 

General  Description. — Sweetened  condensed  milk  may  de- 
velop a  distinctly  rancid  flavor  and  odor,  a  defect  which  renders 
it  unmarketable. 

According  to  the  best  authority,  there  are  many  agents  which 
may  be  active  in  the  production  of  rancidity.  The  fact  that  in 
rancid  butter  are  usually  found  to  predominate  certain  species  of 
organisms,  such  as  the  fungi  of  Penicilium  Glaucum,  Penicilium 
Roqueforti,  Cladosporium  butyri,  Oidium  lactis,  Actinomycoces 
odorifora,  yeast  and  various  bacterial  species,  such  as  Bacterium 
fluorescens,  pjacterium  prodigiosum,  Bacillus  mesentericus,  etc., 
and  that  these  species  are  capable  of  making  butter  rancid,  has 
led  to  the  conclusion  that  they  may  be  the  cause  of  rancidity, 
either  by  direct  action,  or  by  the  secretion  of  fat-splitting  en- 
zymes. It  is,  therefore,  quite  possible  that  some  of  these  species, 
or  similar  groups  of  species,  may  be  instrumental  in  developing 
rancidity  in  sweetened  condensed  milk.  It  has  been  further 
found  that  the  milk  products  from  certain  individual  cows,  or 
cows  under  certain  physiological  conditions  are  more  prone  to 
develop  a  rancid  flavor,  than  milk  products  from  other  cows  or 
cows  under  other  conditions. 

2  Hunziker,  Results  not  published. 


SWEETENED  CONDENSED  MILK  DEFECTS  213 

Relation  of  Polluted  Water  to  Rancidity.— Polluted  and  filthy 
water  is  usually  contaminated  with  fungi  and  bacteria  belonging 
to  the  species  enumerated  above  and  which  have  been  found  to 
be  able  to  produce  rancidity.  It  is,  therefore,  not  improbable, 
where  such  water  is  used  in  the  factory  in  the  washing  of  cans, 
conveyors,  kettles,  pipes,  etc.,  in  the  condenser  of  the  vacuum 
pan  and  in  the  cooling  tanks,  as  is  frequently  the  case,  that  the 
contamination  of  milk  with  it  may  result  in  the  development 
of  rancidity. 

Relation  of  Climate  to  Rancidity. — It  is  frequently  claimed 
that  condensed  whole  milk  shipped  to  the  tropics  turns  rancid, 
owing  to  exposure  of  this  milk,  rich  in  fat  to  a  warm  climate. 
Advantage  is  sometimes  taken  of  this  argument,  to  justify  viola- 
tions of  the  law  by  skimming  all,  or  a  part  of  the  milk  before 
condensing.  This  matter  has  been  thoroughly  investigated.  All 
experimental  results  show  that  sweetened  condensed  milk,  made 
properly  and  in  conformance  with  the  law,  and  containing  all 
the  butter  fat  of  the  original  whole  milk,  does  not  turn  rancid 
at  any  temperature. 

Putrid  Sweetened  Condensed  Milk. 

General  Description. — Sweetened  condensed  milk  is  best 
when  fresh.  With  age  it  gradually  develops  a  stale  flavor  which 
frequently  develops  into  a  putrid  odor  and  flavor. 

Causes  and  Prevention. — The  purer  the  fresh  milk  and  the 
cane-sugar,  and  the  more  careful  the  processor,  the  longer  will 
the  condensed  milk  retain  its  pleasant  flavor,  provided  that  it  is 
stored  at  a  reasonably  low  temperature.  Age,  however,  will 
cause  the  best  sweetened  condensed  milk  to  become  stale.  The 
appearance  of  the  stale  flavor  is  usually  hastened  when  heating 
the  fresh  milk  with  direct  steam;  also,  where  the  fresh  milk  is 
not  heated  to  a  sufficiently  high  temperature  (below  176  de- 
grees F.)  the  condensed  milk  will  break  down  rapidly  with  age, 
usually  developing  a  putrid  flavor  and  odor.  This  defect  rarely 
appears  where  the  fresh  milk  is  heated  to  180  degrees  F.  or 
above.  This  phenomenon  is  probably  due  to  the  presence  in 
milk  of  active  enzymes,  such  as  galactase,  gradually  decompos- 
ing the  proteids.  The  action  of  most  of  these  enzymes  is 
destroyed  when  the  milk  is  heated  to  176  degrees  F.  or  above. 


214  SWEETENED  CONDENSED  MILK 

Metallic  Sweetened  Condensed  Milk. 

General  Description. — Sweetened  condensed  milk  frequently 
is  pregnant  with  a  very  distinct  metallic  flavor  suggesting  copper. 

Causes  and  Prevention. — This  can  usually  be  traced  back  to 
an  unsanitary  condition  of  the  dome  of  the  vacuum  pan.  The 
sugar  and  acid  in  the  boiling  milk  in  the  pan  tend  to  cause  the 
formation  of  copper  oxide  and  copper  salts,  on  those  sections  of 
the  interior  surface  of  the  pan  which  are  not  daily  completely 
cleansed. 

The  dome  of  the  pan  is  neglected  in  many  condenseries  from 
the  standpoint  of  thorough  cleaning.  If  it  is  permitted  to  go 
uncleansed  for  a  considerable  period  of  time,  it  becomes  coated 
with  copper  salts  and  when  the  pan  is  again  in  operation,  the 
boiling  milk  and  its  spray  wash  these  metallic  salts  down 
incorporating  them  in  the  condensed  milk. 

That  the  copper  in  the  dome  is  being  acted  on  can  be  very 
readily  determined  by  wiping  the  inside  surface  of  the  dome  off 
with  a  wet  sponge,  then  analyzing  the  expressed  liquid  that 
the  sponge  has  absorbed.  This  liquid  will  be  found  to  contain 
varying  amounts  of  cppper7  according  to  the  state  of  cleanness 
of  the  dome. 

In  order  to  avoid  metallic  flavor  in  sweetened  condensed 
milk,  the  dome  should  be  washed  down  daily  with  similar  care 
as  is  given  the  cleansing  of  the  jacket,  body  and  coils,  and  each 
morning,  before  the  milk  is  allowed  to  enter  the  pan,  the  entire 
pan,  including  dome  and  gooseneck,  should  be  thoroughly  rinsed 
down  with  plenty  of  clean  water. 

•    Brown  Sweetened  Condensed  Milk 

General  Description. — Some  of  the  sweetened  condensed 
milk  on  the  market  has  a  brown  color,  suggesting  chocolate  pud- 
ding. In  this  condition  it  is  usually  rejected  by  the  consumer. 

Causes  and  Prevention. — All  sweetened  condensed  milk  not 
held  at  a  low  temperature  grows  darker  in  color  with  age.  If 
manufactured  properly  and  not  exposed  to  unfavorable  condi- 
tions, this  brown  color  appears  very  gradually  and  not  until  the 
condensed  milk  is  many  months  old.  If  exposed  to  high  temper- 
ature in  storage  or  transportation,  when  stowed  against  the 
boiler  room  in  the  hold  of  the  steamer,  or  laying  on  the  shelves 


UNSWEETENED  CONDENSED  MILK  DEFECTS  215 

of  the  warm  grocery  store  or  drug  store,  etc.,  it  turns  brown 
rapidly.  Condensed  milk  in  cold  storage  retains  its  natural  color 
indefinitely.  Where  milk  is  recondensed  (the  condensed  milk 
is  redissolved  either  in  water  or  in  fresh  milk  and  condensed  a 
second  time),  the  product  is  always  darker  in  color.  This  brown 
color  is  due  to  the  oxidizing  action  of  heat  on  both,  the  lactose 
and  the  sucrose,  a  portion  of  the  sugar  caramelizing.  Experience 
has  shown  that  the  sugar  is  more  sensitive  to  the  oxidizing 
action  of  the  heat  of  recondensing,  than  when  condensed  the 
first  time. 

CHAPTER  XXIV. 

DEFECTIVE  EVAPORATED  MILK  AND  PLAIN 
CONDENSED  BULK  MILK 

The  following  are  the  chief  defects  of  unsweetened  condensed 
milk :  curdy,  grainy,  separated  and  churned,  blown  or  fermented, 
brown,  gritty,  metallic. 

Curdy,  Plain  Condensed  Milk  and  Evaporated  Milk 

General  Description. — Curdy,  unsweetened  condensed  milk 
is  a  term  used  for  milk  in  which  a  part  of  the  casein  is  precip- 
itated in  the  form  of  lumps  of  various  sizes.  The  appearance 
of  lumps  of  curd  in  this  product  is  a  defect  that  may  render  the 
goods  unsalable. 

Causes  and  Prevention. — Lumps  are  usually  due  to  a  poor 
quality  of  fresh  milk,  the  use  of  excessive  heat  in  the  sterilizing 
process  and  too  high  a  degree  of  concentration. 

Lumps  in  Plain  Condensed  Bulk  Milk. — Lumps  are  prone  to 
appear  in  plain  condensed  bulk  milk,  as  this  class  of  goods  is 
usually  made  from  fresh  milk  that  may  be  slightly  sour,  as  is  the 
case  in  creameries  and  in  milk  plants  where  the  surplus  and  the 
returned  milk  is  often  manufactured  into  plain  condensed  bulk 
milk.  This  defect  can  be  avoided  by  neutralizing  the  milk  before 
heating,  with  an  alkali  (sodium  bicarbonate  or. lime  water),  heat- 
ing less  intensely,  by  not  carrying  the  condensing  process  quite 
so  far.  If  the  plain  condensed  bulk  milk  comes  from  the  pan  in 
lumpy  condition,  it  can  usually  be  reduced  to  a  smooth  body  by 
passing  it  through  an  ice  cream  freezer  at  ordinary  temperatures. 


216  UNSWEETENED  CONDENSED  MILK  DEFECTS 

Lumps  of  Curd  in  Evaporated  Milk. — The  danger  of  lump- 
iness,  or  curdiness  in  evaporated  milk  is  greatly  augmented  by 
the  fact  that,  in  addition  to  the  causes  named  under  plain  con- 
densed bulk  milk,  the  sterilizing  process  must  be  dealt  with. 
The  high  sterilizing  temperature  used,  tends  to  precipitate  the 
proteids  of  milk,  and  the  temperature  cannot  be  reduced  below 
certain  limits  without  impairing  the  keeping  quality  of  the  pro- 
duct. Most  of  the  evaporated  milk,  after  sterilization,  is  sub- 
jected to  the  shaking  process  in  which  the  coagulum  in  the  cans 
is  reduced  to  a  homogeneous  creamy  fluid,  provided  that  the  curd 
is  not  too  hard.  A  curd  will  form  in  the  sterilizer  in  the  majority 
of  cases.  If  it  is  soft  enough,  so  that  it  can  be  completely  broken 
up,  no  harm  is  done.  If  it  is  so  firm  that  mechanical  shaking 
fails  to  cause  it  to  disappear,  then  the  evaporated  milk  will  reach 
the  market  in  lumpy  condition  and  is  difficult  to  sell. 

Effect  of  Quality  of  Fresh  Milk. — The  quality  of  fresh  milk 
is  all  important  in  preventing  lumpy  evaporated  milk.  The  milk 
must  come  from  healthy  cows  in  good,  normal  physical  condition. 
It  must  not  contain  colostrum  milk  nor  be  stripper  milk  and  it 
must  receive  the  best  of  care  on  the  farm  and  reach  the  factory 
perfectly  sweet.  Milk  that  is  not  of  high  quality  in  every  respect 
should  not  be  received  at  the  factory.1 

Effect  of  Concentration. — The  more  concentrated  the  evap- 
orated milk,  the  greater  the  danger  of  lumpiness.  All  the  con- 
ditions causing  lumpiness  are  intensified  by  the  degree  of  con- 
centration. The  manufacturer  must,  therefore,  study  the  be- 
havior of  his  product  at  different  degrees  of  concentration,  and 
then  decide  how  much  evaporation  it  will  stand  without  develop- 
ing subsequently  a  permanent  curd  in  the  sterilizer.1 

Effect  of  Sterilization. — The  coagulum  is  formed  in  the 
sterilizer.  The  higher  the  temperature,  other  conditions  being 
the  same,  the  firmer  the  curd.  The  lowest  temperature  that  will 
efficiently  sterilize  the  evaporated  milk  should,  therefore,  be 
used.  Since  the  sterilizing  temperature  to  be  maintained  cannot 
be  modified  below  certain  limits,  it  is  necessary,  when  the  milk 
is  very  sensitive  to  the  heat,  to  lower  the  degree  of  concentration. 
In  some  factories  fractional  sterilization  is  resorted  to  with 


i  For  detailed  discussion  of  relation  of  quality  of  fresh  milk  to  curdiness  of 
evaporated  milk  see  Chapter  VIII  on  "Manufacture  of  Evaporated  Milk,"  "Quality 
of  Fresh  Milk,"  p.  104. 


UNSWEETENED  CONDENSED  MII^K  DEFECTS  217 

batches  of  milk  that  are  suspicious.  By  so  doing,  lower  tem- 
peratures can  be  used  effectively,  but  this  process  calls  for  much 
more  labor,  increases  the  cost  of  manufacture  and  decreases  the 
capacity  of  the  factory. 

Effect  of  Fractional  Curdling. — Experience  has  shown  that, 
if  the  proteids  in  evaporated  milk  are  partly  precipitated  by  heat 
before  the  milk  reaches  the  sterilizer,  the  curd,  or  lumps  formed 
in  the  sterilizer  are  less  firm  and  can  be  shaken  out  more  readily. 
It  is,  therefore,  advisable  to  heat  the  milk  in  the  forewarmers  to 
as  near  the  boiling  point  as  possible  and  to  hold  it  at  that  tem- 
perature for  at  least  five  minutes  before  it  is  drawn  into  the  pan. 
The  superheating  of  the  evaporated  milk  before  it  leaves  the  pan 
is  an  additional  safeguard  against  the  formation  of  excessive  curd 
in  the  sterilizer. 

Effect  of  Homogenizing  Evaporated  Milk. — Excessive  pres- 
sure in  the  homogenizer  tends  to  so  change  the  physical  prop- 
erties of  the  casein  as  to  render  it  more  sensitive  to  the  steriliz- 
ing process.  Evaporated  milk,  homogenized  under  excessive 
pressure  almost  invariably  forms  a  firm,  unshakable  curd  in  the 
sterilizer.  The  homogenizing  pressure  should  be  kept  down  to 
one  thousand  to  fifteen  hundred  pounds.2 

Acid  Flux  in  the  Cans  Causes  Lumps.— Similar  as  in  the  case 
of  the  sweetened  condensed  milk,  the  presence  of  acid  flux  in  the 
cans  of  evaporated  milk  causes  lumpiness.  The  acid  that  reaches 
the  interior  of  the  cans  causes  the  milk  coming  in  contact  with 
the  seams  to  curdle.  Only  acid-free  flux  should  be  used  in  the 
manufacture  and  sealing  of  the  cans. 

Grainy  Evaporated  Milk 

General  Description. — This  term  is  sometimes  applied  to 
lumpy  milk,  in  which  case  it  means  the  same.  By  grainy  milk, 
however,  is  generally  understood  milk  which  contains  a  sediment 
of  a  white  granular  appearance,  which  is  insoluble. 

Causes  and  Prevention. — This  granular  sediment  is  largely 
found  in  the  hermetically  sealed  cans  after  the  sterilizing  process. 
It  is  due  to  excessively  high  sterilizing  temperatures  or  too  long 


1  For  detailed  discussion  of  relation  of  concentration  to  curdiness  of  evap- 
orated milk  see  Chapter  VIII  on  "Striking." 

8  For  detailed  discussion  of  the  effect  of  homogenizing  on  curdiness  see 
Chapter  IX  on  "Homogenizing"  and  Chapter  XXIV  on  "Separated  and  Churned 
Evaporated  Milk." 


218  UNSWEETENED  CONDENSED  MILK 

exposure  of  the  milk  to  the  process.  It  consists  largely  of  the 
mineral  matter  of  milk,  rendered  insoluble  and  precipitated  by 
heat.  The  use  of  lower  sterilizing  temperatures  or  the  shorten- 
ing of  the  period  of  sterilization  will  help  to  avoid  this  defect. 
Evaporated  milk  in  the  condensation  of  which  the  "Continu- 
ous Concentrator"  was  used,  has  a  tendency  to  show  slight  grainy 
condition,  though  this  is  barely  perceptible. 

Separated  and  Churned  Evaporated  Milk 

General  Description. — This  is  a  very  common  defect.  A 
portion  of  the  butter  fat  of  the  contents  of  the  hermetically 
sealed  cans,  has  separated  and  appears  in  the  form  of  lumps  of 
cream  or  of  churned  butter,  on  top  of  the  evaporated  milk.  While 
this  separated  evaporated  milk  is  normal  in  quality  and  whole- 
someness,  its  appearance  condemns  it. 

Causes  and  Prevention. — As  explained  in  Chapter  IX  on 
"Homogenizing,"  p.  110,  the  fundamental  cause  of  separated  and 
churned  evaporated  milk  lies  in  the  difference  of  the  specific 
gravity  between  the  butter  fat  and  the  rest  of  the  milk  constitu- 
ents. The  fat  globules,  being  lighter  than  the  serum,  tend  to 
rise  to  the  surface,  forming  a  layer  of  thick  cream.  When  this 
separated  evaporated  milk  is  subjected  to  agitation,  as  is  the 
case  in  transportation,  this  'cream  churns  into  lumps  of  butter. 
This  tendency  of  the  fat  to  separate  in  storage  and  churn  in 
transportation,  increases  with  the  increase  of  the  size  of  the  fat 
globules,  because  the  larger  the  globules,  the  larger  is  their  cubic 
content  in  proportion  to  their  surface.  This  fact  is  based  on  the 
well  known  physical  law,  that  the  surfaces  of  two  spheres  are 
to  each  other  as  the  squares  of  their  diameters,  and  the  cubic 
contents  of  two  spheres  are  to  each  other  as  the  cubes  of  their 
diameters.  The  cubic  contents  determine  the  gravity  force,  or 
.buoyancy,  while  the  surfaces  control  the  resistance  force.  There- 
fore, the  larger  the  fat  globules  the  greater  is  their  buoyancy 
and  the  weaker  is  the  relative  resistance  wrhich  they  must  over- 
come in  their  upward  passage. 

Effect  of  Locality  and  Season. — Since  the  predominating 
size  of  fat  globules  in  milk,  varies  with  breed  and  period  of 
lactation  of  the  cows,  the  ease  with  which  evaporated  milk 
separates  and  the  difficulty  of  overcoming  this  defect,  differ 


UNSWEETENED  CONDENSED  MII.K  DEFECTS 


219 


greatly  with  locality  and  season  of  year.  The  fat  globules  in 
milk  from  the  Channel  Island  breeds,  average  two  to  three  times 
as  large  as  those  in  milk  from  the  Holsteins  and  Ayrshires. 
Therefore,  factories  located  in  Holstein  and  Ayrshire  territories 
are  not  troubled  nearly  as  much  with  fat  separation  in  evapo- 
rated milk, 'as  factories  in  localities  where  Jerseys  and  Guernseys 
predominate. 

Again,  the  fat  globules  are  largest  at  the  beginning  of  the 
period  of  lactation  and  decrease  in  size  as  the  period  of  lactation 
advances. 

Relation  of  Breed  and  Period  of  Lactation  to  Size  of  Fat 

Globules1 


Months  of  period 

Breeds  of 

3  airy  cows 

of  lactation 

Jersey 
25  cows 

Guernsey 
20  cows 

Holstein 
9  cows 

Ayrshire 
33  cows 

Holderness 
20  cows 

Devon 
16  cows 

1st  month  

1104 

928 

687 

546 

2nd      " 

1098 

1063 

640 

580 

661 

585 

8rd               

1228 

954 

576 

624 

607 

450 

4th 

1097 

659 

256 

426 

501 

547 

5th               _ 

1149 

839 

396 

384 

397 

319 

6th               
7th               
8th               . 

846 
1017 
733 

737 
584 
568 

595 
340 
310 

399 
322 

298 

324 
329 
379 

355 
270 
20) 

9th               

10th 

715 
571 

408 
426 

384 
284 

241 

248 

315 
336 

250 
228 

Average  for  year  

955.8 

716.6 

420.1 

420.9 

427.6 

375 

In  order  to  equalize  the  output  of  evaporated  milk  through- 
out the  year,  condensing  concerns  make  every  effort  to  induce 
their  patrons  to  time  the  breeding  of  their  cows  in  such  a  way 
that  the  fresh  cows  are  distributed  throughout  the  year.  The 
result  of  this  practice  is,  that  the  milk  supply  of  these  factories 
represents  at  all  times  a  mixture  of  milk  from  cows  at  all  stages 
of  their  period  of  lactation.  This  naturally  equalizes  the  be- 
havior of  the  finished  product  as  far  as  separation  of  the  fat  is 
concerned,  facilitating  the  control  of  this  separation.  On  the 
other  hand,  in  localities  of  factories,  newly  established,  summer 
milk  is  largely  produced  and  the  majority  of  cows  freshen  in  the 
spring.  This  causes  a  marked  increase  of  the  size  of  the  average 
fat  globules  in  early  summer,  rendering  the  manufacture  of 
evaporated  milk,  that  does  not  separate  its  fat,  more  difficult. 


1  Hunziker,   Mills  and   Spitzer,   "Moisture  Control   of  Butter."   Indiana  Agri- 
cultural Experiment  Station,  Bulletin  No.   159,   1912,   pp.   330-334. 


220  UNSWEETENED  CONDENSED  MILK  DEFECTS 

Effect  of  Degree  of  Concentration. — Other  conditions  being 
the  same,  the  more  concentrated  the  product  the  less  the  danger 
of  fat  separation  in  the  finished  product.  The  reason  for  this 
lies  in  the  fact  that  with  the  concentration  the  viscosity  and  the 
resistance  force  of  the  evaporated  milk  increase,  hindering  the 
fat  globules  in  their  upward  passage.  This  is  partly  offset  by 
the  increase  in  the  specific  gravity  of  the  product,  but  the  in- 
crease of  the  resistance  force  exerts  a  stronger  influence  against 
separation  of  the  fat,  than  the  increase  of  the  gravity  force  exerts 
in  favor  of  fat  separation. 

However,  as  the  concentration  increases,  the  evaporated 
milk  becomes  more  sensitive  to  the  sterilizing  process  and 
beyond  certain  limits  it  would  be  necessary  to  reduce  the  tem- 
perature or  the  length  of  exposure  to  heat,  or  both,  in  order  to 
prevent  the  more  highly  concentrated  milk  from  becoming  per- 
manently curdy.  If,  in  order  to  increase  the  viscosity,  the  degree 
of  concentration  is  carried  so  far  that  the  sterilizing  process  has 
to  be  shortened,  nothing  is  gained  but  much  may  be  lost.  It 
is  obvious,  therefore,  that  the  degree  of  concentration  does  not 
furnish  a  practical  basis  for  controlling  fat  separation. 

Effect  of  the  Sterilizing  Process. — Prolonged  exposure  of 
the  evaporated  milk  to  the  sterilizing  heat  tends  to  so  change  the 
physical  properties  of  the  albuminoids,  as  to  render  the  product 
more  viscous.  Within  the  limits  of  the  necessary  sterilizing  heat, 
long  exposure  to  moderate  heat  is  more  effective  in  this  respect 
than  short  exposure  to  a  high  degree  of  heat.  Since  the  greater 
viscosity  tends  to  keep  the  fat  globules  from  rising,  the  use  of 
a  prolonged  sterilizing  process,  in  which  the  heat  is  applied 
slowly,  is  more  effective  in  preventing  fat  separation  in  the 
evaporated  milk  than  a  rapid,  short  process,  in  which  the  tem- 
perature used  is  very  high. 

It  should  be  understood  from  the  discussion  in  previous 
chapters  that,  in  regulating  the  process  of  sterilization,  the  pro- 
cessor should  be  governed  by  the  condition  and  behavior  of  the 
milk  and  that  on  the  one  hand  the  degree  and  duration  of  heat 
should  always  be  sufficient  to  insure  absolute  sterility  of  the 
product,  while  on  the  other  he  must  guard  against  the  formation 
of  an  unshakable  curd.1 


1  For  detailed  discussion  see  Chapter  XI  on  "Sterilizing,"  page  120. 


UNSWEETENED  CONDENSED  MILK  DEFECTS  221 

Effect  of  Superheating. — The  superheating  of  the  milk  before 
sterilization  and  the  stopping  of  the  reel  of  the  sterilizer  as  ex- 
plained under  "Sterilization,"  page  120,  also  tend  to  so  increase 
the  viscosity  of  the  evaporated  milk  as  to  minimize  its  tendency 
to  separate  its  fat.  But  here  again  good  judgment  is  required, 
otherwise  there  is  danger  of  spontaneous  thickening  of  the  prod- 
uct after  manufacture. 

Turning  the  Cans  in  Storage. — Many  manufacturers,  in  an 
effort  to  avoid  fat  separation,  have  adopted  the  practice  of  turn- 
ing their  goods  in  storage  at  regular  intervals.  This  operation 
naturally  interferes  with  and  retards  the  rising  of  the  fat  to  the 
surface,  as  long  as  the  goods  remain  in  the  factory.  After  they 
leave  the  factory  this  control  must  of  necessity  cease  and  if  the 
evaporated  milk,  owing  to  the  process  of  manufacture  and  the 
condition  of  the  product,  is  destined  to  separate  its  fat,  the  turn- 
ing of  the  cases,  while  at  the  factory,  cannot  permanently  prevent 
separation.  Where  the  goods  are  consumed  immediately  after 
they  leave  the  factory,  this  practice  may  serve  the  purpose ;  but, 
since  the  large  bulk  of  evaporated  milk  manufactured,  is  exposed 
to  prolonged  storage,  its  advantage  is  very  limited. 

Effect  of  Homogenizing. — Under  average  conditions  careful 
attention  to  the  precautions  above  discussed  will  greatly  mini- 
mize and  often  prevent  fat  separation.  At  best,  however,  much 
of  the  evaporated  milk  on  the  market  shows  signs  of  separation 
after  sixty  to  ninety  days  and  some  of  it  even  after  two  weeks, 
for  the  fundamental  cause  of  separation,  the  difference  in  gravity 
between  the  fat  globules  and  the  rest  of  the  milk  constituents, 
is  still  present;  then  again,  under  less  favorable  conditions,  even 
the  above  precautions  may  not  prove  adequate  to  keep  the  fat 
from  separating. 

The  introduction  of  any  agent  or  process,  therefore,  capable 
of  permanently  removing  this  fundamental  cause,  must  prove 
a  lasting  benefit  to  the  manufacturer  of  evaporated  milk.  This 
agent  has  been  found  in  the  homogenizer.  The  homogenizer 
makes  it  possible  to  divide  the  fat  globules  so  finely,  that  their 
buoyancy  or  gravity  force  is  not  great  enough  to  overcome  the 
resistance  of  the  surrounding  liquid.  They  are  unable  to  rise  to 
the  surface,  but  remain  in  homogeneous  emulsion. 

It  is  quite  probable  that  aside  from  the  reduction  of  the  size 


222  UNSWEETENED  CONDENSED  Miuc  DEFECTS 

of  the  fat  globules,  the  efficiency  of  the  homogenizer  to  prevent 
fat  separation  is  due  also  to  the  physical  change  of  the  casein  as 
the  result  of  homogenization.  The  casein  becomes  more  viscous. 
The  chief  objection  to  the  use  of  the  homogenizer  is  its 
effect  on  the  casein  of  the  milk,  when  subjected  to  excessive  pres- 
sure. Beyond  certain  limits  of  pressure  homogenization  so 
affects  the  casein,  that  the  latter  is  more  prone  to  curdle  in  the 
sterilizer.  However,  experience  has  amply  shown  that  the  maxi- 
mum pressure  required  to  prevent  fat  separation  in  the  finished 
product,  is  not  great  enough  to  seriously  affect  the  behavior  of 
the  casein  during  sterilization.  Hence,  the  proper  regulation  of 
the  pressure  and  the  intelligent  use  of  the  homogenizer,  furnish 
a  satisfactory  and  reliable  means  to  prevent  fat  separation.  Under 
average  conditions,  the  use  of  sufficient  pressure  to  reduce  the 
fat  globules  to  one-third  of  their  original  size,  practically 
destroys  the  power  of  the  fat  globules  to  rise  to  the  surface.  A 
pressure  of  approximately  one  thousand  pounds  per  square  inch, 
makes  possible  this  reduction  of  the  size  of  the  fat  globules.1 

Fermented  Evaporated  Milk. 

General  Description. — Fermented  evaporated  milk  is  evap- 
orated milk,  which  after  sterilization,  has  undergone  fermenta- 
tion. The  type  of  fermentations  found  in  this  product  varies 
with  locality,  season  of  year  and  factory  conditions.  The  con- 
tents of  the  cans  may  have  soured  with  curd  formation,  or  a 
curd  may  have  formed  without  acid  development,  or  the  fer- 
mentation may  be  gaseous,  in  which  case  the  cans  bulge,  and 
these  gaseous  fermentations  may  be  accompanied  by  acid  forma- 
tion or  by  putrefactive  products.  In  all  cases  of  fermented  milk 
the  product  is  entirely  worthless.  These  defects  are  usually, 
though  not  always,  detected  during  the  period  of  incubation. 

Fermented  evaporated  milk  is  the  result,  either  of  incomplete 
sterilization,  or  of  leaky  cans.  The  causes  of  fermented  evapo- 
rated milk  differ  with  the  specific  type  of  fermentations  produced ; 
they  will  be  discussed  separately  and  as  relating  to  the  respective 
types  of  fermentations. 

Acid  Fermentation,  Sour,  Curdled,  Evaporated  Milk 

1  For  details  on  the  use  of  homogenizer  see  Chapter  IX  on  "Homogenizing," 
page  105. 


UNSWEETENED  CONDENSED  MILK  DEFECTS  223 

General  Description. — Upon  opening  the  cans  the  contents 
are  found  to  be  sour  and  curdy. 

Causes  and  Prevention. — This  condition  is  the  result  of  the 
presence  of  acid  producing  species  of  micro-organisms,  usually 
of  the  lactic  acid  type,  which  sour  the  milk,  and  the  acid  produced 
curdles  the  casein.  Since  the  majority  of  the  lactic  acid  bacteria 
are  not  resistant  to  heat  and  are  destroyed  at  relatively  low  heat, 
this  defect  is  not  usually  caused  by  incomplete  sterilization.  The 
temperature  of  sterilization,  though  it  might  be  insufficient  to 
kill  spore  forms,  is  high  enough  to  make  it  impossible  for  lactic 
acid  bacteria  to  pass  the  process  alive. 

The  only  way  in  which  this  defect  can  occur  is  through  sub- 
sequent contamination  of  the  contents  of  the  cans  with  these 
germs,  and  the  only  possible  channel,  through  which  this  sub- 
sequent contamination  may  occur,  is  leaky  cans,  or  leaky  seals. 
A  careful  examination  of  the  cans  of  sour,  curdled  evaporated 
milk  usually  shows  faulty  cans  or  faulty  seals. 

Bitter  Curd 

General  Description. — When  the  cans  are  opened  the  con- 
tents present  a  solid  coagulum,  generally  noticeably  white  in 
color  and  very  bitter  to  the  taste,  similar  to  the  bitterness  of 
dandelions.  There  is  a  separation  of  practically  clear  whey,  the 
curd  does  not  break  down  readily  upon  shaking  and  the  acid 
reaction  of  the  mixture  of  curd  and  whey  is  about  .35  to  .40  per 
cent.,  which  is  normal  for  evaporated  milk. 

Causes  and  Prevention. — Microscopic  examinations  under 
high  magnification  of  cultures  in  sterile  milk  show  the  presence 
of  very  small  bacilli.  The  milk  forms  a  firm  coagulum  in  five  to 
seven  days  and  when  over  one  week  old  the  curd  has  the  same 
strong,  bitter  taste  as  that  in  the  cans.  The  bitterness  increases 
with  age.  These  bacilli  grow  best  at  90  degrees  F.  They  are 
facultative  anaerobes,  developing  both,  in  aerobic  and  anaerobic 
media,  but  prefer  anaerobic  conditions. 

In  the  cases  under  observation  no  spores  were  detected  and 
exposure  for  fifteen  minutes  to  212  degrees  F.  destroyed  these 
germs.  The  above  findings  do  not  exclude  the  possibility  of  spore 
formation  under  conditions  very  unfavorable  to  growth  and  life. 

The  presence  of  this  species  of  bitter  curd  organisms  sug- 
gests incomplete  sterilization  of  the  evaporated  milk.  The  strik- 


224  UNSWEETENED  CONDENSED  MILK  DEFECTS 

ing  whiteness  of  the  curd  in  all  cases  that  have  come  to  the 
writer's  attention,  is  further  proof  of  the  correctness  of  this  de- 
duction. It  indicates  that  these  cans  received  relatively  little 
heat  in  the  sterilizer,  otherwise  the  curd  would  have  a  darker 
color.  This  defect  usually  does  not  show  up  in  all  the  cans  of 
one  and  the  same  batch,  but  only  in  a  limited  portion  of  each 
batch.  This  fact  suggests  that  the  distribution  of  heat  in  the 
sterilizer  is  not  uniform,  some  cans  getting  less  heat  than  others. 

This  defect  occurs  generally  in  summer,  a  fact  which  may  be 
due  to  one  or  both  of  the  following  conditions : 

While  it  is  well  known  that  there  is  a  variety  of  species  of 
bacteria,  yeast  and  torula  that  are  capable  of  producing  a  bitter 
curd,  either  direct,  or  through  the  secretion  of  casein-curdling 
enzymes,  and  while  these  different  species  of  micro-organisms 
come  from  a  variety  of  sources,  the  most  common  sources  are, 
the  soil,  pasture,  water  and  the  udder  itself.  It  is  a  noteworthy 
fact  that  this  defect  is  most  commonly  found  in  milk  and  milk 
products  when  the  cows  are  on  pasture.  It  is,  therefore,  probable 
that,  in  most  cases,  this  troublesome  germ  is  carried  into  the  milk 
on  the  farm. 

Again,  in  summer,  at  a  time  when  this  defect  generally 
occurs,  the  effect  on  the  cows  of  the  summer  heat  and  flies,  and 
the  tendency  toward  high  acid  in  milk,  render  the  milk  most 
sensitive  to  the  sterilizing  heat.  The  operator  finds  it  difficult 
to  avoid  the  formation  of  a  disastrous  curd  in  the  sterilizer.  In 
order  to  guard  against  this  trouble  he  is  tempted  to  either  lower 
the  temperature,  or  shorten  the  duration  of  the  sterilizing  process. 
This  tends  towards  incomplete  sterilization.  A  very  frequent 
result  of  this  incomplete  sterilization  in  the  early  summer 
months,  is  the  formation  of  a  bitter  curd.  When  the  processor 
returns  to  the  proper  sterilizing  process,  the  occurrence  of  bitter 
curd  in  the  cans  disappears  and  the  product  is  normal. 

A  further  safeguard  against  the  recurrence  of  this  trouble 
lies  in  providing  for  uniform  distribution  of  heat  in  the  sterilizer. 
If  the  cans  have  to  be  stacked  in  deep  tiers,  which  is  un- 
desirable and  should  be  avoided,  slats  should  be  placed  over 
the  top  of  every  second  row  of  cans.  This  will  make  possible 
the  free  access  of  steam  to  at  least  one  end  of  each  can.  If  the 
circulation  of  steam  in  the  sterilizer  is  poor,  the  uniform  distribu- 


UNSWEETENED  CONDENSED  MILK  DEFECTS  225 

tion  of  heat  can  be  facilitated  by  filling1  the  sterilizer  about  one- 
third  full  of  water  so  that,  with  every  revolution  of  the  frame- 
work, the  cans  have  to  pass  through  this  water  once.  The  water 
reaches  every  nook  in  the  interior  of  the  sterilizer,  distributing 
the  heat  much  more  uniformly  than  the  steam.  If  these  pre- 
cautions fail  to  remedy  the  trouble,  then  the  entire  process  is 
inadequate  and  either  more  heat,  or  longer  exposure  to  the  same 
heat  is  necessary. 

It  is  obviously  imperative  that  the  fresh  milk,  as  it  arrives 
at  the  factory,  be  subjected  to  the  most  rigid  inspection  on  the 
platform,  in  order  to  guard  against  the  processing  of  unduly  con- 
taminated milk. 

Blown  Evaporated  Milk  (Gaseous  Fermentation) 
General  Description. — The  ends  of  the  cans  bulge  out  very 
noticeably,  frequently  so  much  so  that  the  seams  of  the  cans 
burst  open.  This  is  due  to  gaseous  fermentation  causing-  high 
pressure  in  the  cans.  The  pressure  is  often  so  great  that  upon 
opening  the  cans,  most  of  the  contents  are  blown  out  with  tre- 
mendous force.  In  some  cases  of  blown  evaporated  milk,  the 
contents  have  an  acid  odor,  pleasant  and  aromatic.  In  most 
instances,  however,  they  give  off  very  foul  odors  and  suggesting 
hydrogen  sulfide,  not  unlike  aggravated  cases  of  Limburger 
cheese.  These  odors  are  exceedingly  penetrating  and  difficult  to 
remove  from  anything  they  come  in  contact  with. 

Causes  and  Prevention. — The  bacteria  causing-  gaseous  fer- 
mentations in  evaporated  milk  usually  belong  to  the  anaerobic 
group  of  butyric  acid  species  and  in  most  cases,  though  not  al- 
ways, the  putrefactive  types  prevail,  such  as  Bacillus  putrificus, 
Plectridium  novum  and  Plectridium  foetidum,  especially  the  lat- 
ter, because  of  its  extraordinary  power  of  resistance  to  heat. 
Plectridium  foetidum  is  an  obligatory  anaerobe  and  it  absolutely 
refuses  to  grow  under  aerobic  conditions.  It  is  an  actively  motile, 
medium-sized  organism  with  flagella  and  spores.  At  one  end  it 
has  an  Indian  club-like  enlargement,  in  wrhich  appears  the  spore. 
The  bacillus  resembles  a  kettle-drum  stick  similar  to  B.  tetani. 
Under  strictly  anaerobic  conditions,  and  incubated  at  90  degrees 
F.,  it  ferments  milk  in  four  days.  The  milk  first  curdles,  then 
gradually  the  curd  dissolves  (digests)  completely,  leaving  a  clear 


226 


UNSWEETENED  CONDENSED  MILK  DEFECTS 


yellow  liquid,  similar  in  appearance  to  butter  oil.  The  fermenta- 
tion is  accompanied  by  the  evolution  of  a  penetrating  foul  odor. 
This  organism  survives  exposure  for  15  minutes  to  245  degrees 
F.  Its  thermal -death  point  lies  between  245  and  250  degrees  F. 
Plectridium  foetidum,  as  well  as  most  of  the  other  species  of 
anaerobic,  spore — bearing  butyric  acid  bacilli  and  bacteria,  is 
present  abundantly  in  cultivated  soil,  in  field  crops  and  even  on 
the  kernels  of  the  grain.  Since  this  type  of  evaporated  milk 
defect  is  characteristic,  especially,  of  the  product  manufactured 
during  the  late  summer  and  early  fall  months,  it  is  very  probable 
that  the  dust  incident  to  the  harvesting  of  the  field  crops,  fur- 
nishes the  chief  source  of  contamination  of  the  milk. 


Fig.  56.     The  result  of  gas- 
eous   fermentation 


Fig.  57.  Plectridium  foetidum,  a 
highly  resistant  species  of  an- 
aerobic microorganisms,  caus- 
ing "swell  heads"  of  evapo- 
rated milk 


In  order  to  avoid  the  occurrence  of  blown,  fermented,  evapo- 
rated milk,  therefore,  it  is  necessary  to  employ  the  highest  steriliz- 
ing temperatures,  or  the  longest  exposure  to  the  sterilizing  heat, 
or  both,  consistent  with  freedom  of  the  milk  from  curdiness.  Ex- 
perience has  shown  that  the  use  of  the  ranges  of  temperature  and 
time  of  exposure,  given  under  Chapter  XI  on  "Sterilizing,"  guard 
effectively  against  this  defect. 

Blown  Evaporated  Milk  Due  to  Freezing. — If  the  evapo- 
rated milk  is  exposed  to  storage  temperatures  below  the  freezing 
point  of  water,  the  contents  of  the  cans  will  freeze.  While  freez- 
ing, the  contents  expand  sufficiently  to  cause  the  ends  of  the  cans 
to  bulge.  When  the  cans  are  subsequently  transferred  to  warmer 


UNSWEETENED  CONDENSED  MILK  DEFECTS  227 

temperatures,  so  that  their  contents  melt  again,  the  milk  contracts 
and  the  cans  resume  their  normal  shape. 

While  the  wholesomeness  and  flavor  of  the  product  are  not 
affected  by, the  freezing  process,  the  remelted  evaporated  milk 
is  usually  less  smooth  and  often  slightly  grainy.  This  is  due  to 
the  fact  that,  during  the  process  of  freezing,  there  is  a  partial 
separation  of  the  watery  portion  from  the  caseous  material.  The 
casein  contracts  and  the  watery  portion  freezes.  When  melted, 
the  emulsion  is  less  complete  than  it  was  before  freezing.  The 
casein  remains  in  its  contracted  form  and  robs  the  product  of  its 
original  smoothness. 

Blown  Evaporated  Milk  Due  to  Chemical  Action. — While 
properly  processed  evaporated  milk  is  perfectly  sterile,  and  from 
the  biological  point  of  view,  keeps  indefinitely,  the  cans  of  very 
old  evaporated  milk  may  bulge,  as  the  result  of  the  action  of  the 
acid  in  the  milk  on  the  container.  Evaporated  milk  contains 
from  .35  to  .50  per  cent,  acid  (calculated  as  lactic  acid).  When 
the  tin  cans  are  filled  with  the  evaporated  milk,  the  tinplate  is 
bright  and  untarnished,  both,  inside  and  out.  After  the  sterilizing 
process,  the  inside  surface  of  the  cans  is  dark  and  dull.  This  is 
caused  by  the  combined  action  of  acid  and  heat,  which  seems  to 
weaken  the  tinplate.  This  phenomenon  is  further  illustrated  by 
the  fact  that  where  creameries  pasteurize  their  skimmilk  and 
return  it  to  the  patrons  in  the  milk  cans  hot,  the  milk  cans  are 
short-lived ;  they  soon  corrode  and  begin  to  leak. 

The  acid  in  the  evaporated  milk  continues  to  act  on  the  tin- 
plate  of  the  can  after  manufacture  and  in  the  case  of  very  old 
evaporated  milk,  the  acid  may  decompose  a  considerable  part  of 
the  iron.  This  action  is  accompanied  by  the  evolution  of  hydro- 
gen gas,  which  causes  the  cans  to  bulge.  This  action  is  hastened 
by  continued  exposure  of  the  goods  to  high  temperatures  (sum- 
mer heat).  This  fact  was -experimentally  demonstrated,1  also, 
by  scratching  the  bottom  of  tin  cans  on  the  inside  with  a  file, 
then  filling  the  cans  with  a  .4  per  cent,  solution  of  lactic  acid  and 
acetic  acid,  respectively.  After  sealing,  the  cans  were  sterilized 
in  the  autoclave,  so  as  to  avoid  any  possibility  of  bacterial  action. 
After  cooling,  these  sterilized  cans  were  incubated  for  some  time 
at  90  degrees  F.  The  cans  containing  the  dilute  acid  began  to 

1  Hunziker  and   Wright,   Indiana  Agricultural   Experiment   Station.      Results 
not  published. 


228  UNSWEETENED  CONDENSED  MILK  DEFECTS 

swell,    while   the   check   cans,    containing   distilled   water  only, 
remained  normal. 

Brown  Evaporated  Milk 

General  Description. — It  is  the  aim  of  the  processor  to  so 
govern  the  sterilizing  process  as  to  give  the  evaporated  milk  a 
rich,  yellow,  creamy  color.  Frequently,  this  color  limit  is  over- 
stepped to  the  extent  of  imparting  to  the  evaporated  milk  a  brown 
color,  suggesting  coffee  with  milk  in  it.  In  this  condition  evap- 
orated milk  fails  to  appeal  to  the  consumer. 

Causes  and  Prevention. — The  dark  color  in  evaporated  milk 
is  due  to  the  oxidizing  action  of  excessive  heat  on  the  milk  sugar, 
causing  the  milk  sugar  to  caramelize.  This  can  be  avoided  by 
reducing  the  sterilizing  temperature,  or  shortening  the  sterilizing 
process,  or  both.  The  storing  of  evaporated  milk  at  high  temper- 
atures (summer  heat)  also  tends  to  deepen  its  color  with  age. 

Gritty  Plain  Condensed  Bulk  Milk 

General  Description. — Grittiness  in  the  unsweetened  goods 
appears  usually  only  in  the  plain  condensed  bulk  milk.  It  is  a 
defect  which  renders  the  product  undesirable  for  ice  cream 
making. 

Causes  and  Prevention. — The  chief  cause  of  this  defect  is 
too  great  concentration.  Plain  condensed  bulk  milk  which  is  not 
condensed  over  3.5  parts  of  fresh  milk  to  1  part  of  condensed  milk 
does  not  become  gritty.  When  the  concentration  exceeds  4:1, 
the  milk  sugar  begins  to  crystallize  out,  making  the  product 
gritty.  Milk  sugar  requires  about  six  times  its  weight  of  water 
for  complete  solution  in  cold  wrater.  When  condensed  at  the 
ratio  of  4:1  or  over,  the  plain  condensed  bulk  milk  contains  con- 
siderably less  than  five  parts,  by  weight,  of  water  to  one  part 
of  milk  sugar.  This  high  concentration,  together  with  the  prac- 
tice of  storing  this  product  at  refrigerating  temperatures  in  order 
to  preserve  it,  is  responsible  for  the  grittiness.  This  trouble  can, 
therefore,  easily  be  prevented  by  not  condensing  to  quite  as  high 
a  degree  of  concentration. 

Metallic  Evaporated  Milk  and  Plain  Condensed  Bulk  Milk. 

General  Description. — Both  evaporated  and  plain  condensed 
bulk  milk  may  show  a  metallic  and  puckery  flavor,  though  this 
defect  is  rather  rare. 


ADULTERATIONS  OF  CONDENSED  MILK  229 

Causes  and  Prevention. — The  metallic  flavor  may  be  due 
to  the  same  cause  as  metallic  sweetened  condensed  milk,  i.  e.  an 
unsanitary  condition  of  the  vacuum  pan,  in  which  case  its  recur- 
rence can  be  readily  avoided  by  thoroughly  cleaning  all  parts  of 
the  pan  including  the  dome  and  the  goose  neck,  and  rinsing  down 
the  whole  pan  thoroughly  with  clean  water  each  morning  before 
operations  begin. 

Unsweetened  condensed  milk  made  by  the  use  of  the  "Con- 
tinuous Concentrator"  may  have  a  metallic  flavor  when  the 
scrapers  in  this  machine  are  improperly  adjusted,  causing  them 
to  cut  into  the  copper  walls  and  thereby  incorporating  metallic 
copper  in  the  product.  This  source  of  metallic  flavor  can  be 
removed  by  proper  adjustment  of  the  revolving  spider  and  its 
essential  parts. 

Evaporated  milk  may  also  show  a  metallic  flavor  as  the  result 
of  chemical  action  of  the  acid  in  the  milk  on  the  can.  This  occurs 
usually  only  upon  prolonged  storage.  Very  old  evaporated  milk 
is  very  prone  to  have  a  metallic  flavor  from  this  source.  It  is 
obvious  that  this  can  best  be  avoided  by  endeavoring  to  move 
the  goods  sufficiently  rapidly  to  limit  the  age  of  the  milk  to  a 
reasonable  period  of  time. 

Cans,  in  the  manufacture  and  sealing  of  which  an  acid  flux 
is  used,  are  prone  to  give  the  contents  a  puckery,  metallic  flavor, 
due  to  the  zinc  chloride  and  hydrochloric  acid  present.  This  can 
be  avoided  by  using  cans  only  in  the  manufacture  of  which  a 
non-acid  flux,  such  as  gasoline-resin  flux,  is  used,  and  by  using 
a  non-acid  flux  for  sealing  the  filled  cans. 

CHAPTER  XXV. 
ADULTERATIONS  OF  CONDENSED  MILK 

It  is  the  sense  of  the  Federal  Pure  Food  Act  that  the  addition 
to  condensed  milk  of  any  substance  except  sucrose,  and  the  abstrac- 
tion of  any  substance  from  milk  except  water,  is  an  adulteration. 

Skimming. —  Condensed  milk  made  from  partly  or  wholly 
skimmed  milk  must  be  labeled  and  sold  as  condensed  skimmed  milk 
in  order  to  comply  with  the  Pure  Food  regulations.  However,  it 
is  possible  for  condenseries  receiving  fresh  milk,  rich  in  butter  fat, 


230  ADULTERATIONS  OF  CONDENSED 

to  skim  a  part  of  that  milk  and  have  their  product  still  conform 
with  the  food  standards. 

Skimmed  sweetened  condensed  milk  can  readily  be  detected  by 
its  whitish  color,  while  condensed  whole  milk  has  normally  a  rich 
yellow  color.  When  diluted,  to  the  consistency  of  ordinary  milk, 
skimmed  condensed  milk,  both  the  sweetened  and  the  unsweetened, 
foams  very  profusely  when  shaken,  while  diluted  condensed  whole 
milk  behaves  similar  to  ordinary  whole  milk.1 

Addition  of  Artificial  Fats. — In  order  to  lower  the  cost  of 
manufacture,  attempts  have  occasionally  been  made  to  skim  the 
fresh  milk  and  substitute  the  abstracted  fat  by  artificial  fats  of 
animal  or  vegetable  origin. 

Recent  improvements  in  the  method  of  manufacture  have  made 
it  possible  to  manufacture  evaporated  milk,  made  from  skim  milk 
to  which  foreign  fats,  especially  vegetable  oils,  such  as  cocoanut 
oil,  have  been  added.  This  milk  has  every  appearance  of,  and  will 
commercially  keep  as  well  as  genuine  evaporated  milk.  A  repre- 
sentative of  this  imitation  evaporated  milk  is  the  "Hebe"  product. 
This  product  consists  of  skim  milk  to  which  have  been  added  vege- 
table fats  to  replace  the  butter  fat.  The  mixture  is  homogenized  in 
order  to  form  a  complete  emulsion,  then  it  is  evaporated,  filled  in 
cans  and  sterilized  in  a  similar  manner  as  the  genuine  evaporated 
milk. 

The  Federal  law  requires  that  the  composition  and  ingredients 
of  these  imitation  products  appear  plainly  on  the  label  of  the 
package. 

It  should  be  clearly  understood  by  the  manufacturer,  the  dealer 
and  the  consumer  that  this  imitation  milk  is  inferior  to  the  genuine 
evaporated  milk,  in  the  fact  that  it  lacks  the  important  growth-pro- 
moting and  curative  properties  which  are  inherent  in  whole  milk. 
If  sold  on  its  own  merits,  and  in  accordance  with  the  Federal 
law,  there  can  be  no  logical  objection  to  the  imitation  product,  but 
if  offered  to  the  consumer  as  the  genuine  article  the  manufacture 
and  sale  of  imitation  evaporated  milk  is  a  heinous  crime  against 
humanity. 

Experiments  conducted  at  Ohio  State  University,  by  Mr. 
J.  L.  Hutchison,  instructor  in  the  Department  of  Agricultural 


1  For  chemical  tests  of  butter  fat   in  condensed   milk,    see   Chapters   XXXI 
and  XXXII. 


ADULTERATIONS  OF  CONDENSED  Miuc  231 

Chemistry  under  the  direction  of  Professor  O.  Erf,  Chief  of 
Department  of  Dairy  Husbandry  and  Dr.  J.  F.  Lipman,  Professor 
of  Agricultural  Chemistry,  demonstrated  that  "Hebe"  milk,  when 
fed  to  young  white  rats,  resulted  in  malnutrition  accompanied  by 
stunted  growth,  sore  eyes  and  death  of  some  of  the  experimental 
rats,  in  a  similar  manner  as  did  other  rations  in  which  the  fat- 
soluble  vitamines  were  lacking. 

Mothers  who  buy  evaporated  milk  for  feeding  infants  and 
children  should  be  cautioned  to  observe  carefully  whether  or  not 
they  receive  the  genuine  article.  Imitation  evaporated  milk  is  not 
a  baby  food.  Babies  and  growing  children  need  butterfat  for  their 
best  development.  If  canned  milk  is  used  for  infant  feeding,  it 
should  be  made  from  whole  milk  only.  (See  also  pp.  176  to  178). 

Addition  of  Commercial  Glucose. —  Commercial  glucose  be- 
longs to  a  group  of  starch  products  in  which  dextrose  is  the  leading 
constituent.  It  is  manufactured  by  the  action  of  dilute  acids  in 
starch  and  starchy  matter,  or  occasionally  woody  fibre.  In  this 
country  it  is  almost  wholly  made  from  maize  starch. 

Starch  glucose  occurs  in  commerce  in  several  forms,  varying 
from  the  condition  of  pure  anhydrous  dextrose,  through  inferior 
kinds  of  solid  sugar,  to  the  condition  of  a  thick  syrupy  liquid,  color- 
less and  transparent,  resembling  molasses  in  consistency  and  glyce- 
rine in  appearance;  it  contains  a  large  proportion  of  dextrin.  In 
connection  with  the  manufacture  of  condensed  milk  the  term  "glu- 
cose" refers  to  this  thick,  syrupy  liquid.  It  is  added  to  the  con- 
densed milk  with  a  view  of  substituting  a  portion  of  the  sucrose 
and  thus  reducing  the  cost  of  manufacture.  It  has  also  been  sug- 
gested that  the  presence  of  commercial  glucose  in  condensed  milk 
prevents  the  precipitation  of  sugar  crystals.  Experiments  have 
shown,  however,  that  condensed  milk  containing  varying  amounts 
of  glucose,  will  become  sandy  just  as  readily  as  normal  condensed 
milk. 

That  glucose  cannot  be  used  as  a  substitute  for  sucrose,  is 
obvious  from  the  fact  that  its  presence  defeats  the  very  object  for 
which  sucrose  is  added.  Instead  of  serving  as  a  preservative,  as  is 
the  case  with  the  best  refined,  granulated  cane  sugar,  glucose  acts 
as  a  most  effective  fermentative.  It  has  been  explained  that  the 
presence  in  sucrose  of  traces  of  invert  sugar,  or  levulose  and  glu- 
cose, causes  condensed  milk  to  ferment.  Glucose  belongs  to  the 


232  ADULTERATIONS  OF  CONDENSED  MII<K 

monosaccharides.  Its  chemical  formula,  like  that  of  levulose,  is 
C6H12O6,  it  oxidizes  readily  and  under  the  influence  of  yeast  and 
other  micro-organisms  it  ferments,  yielding  mainly  alcohol  and 
carbon  dioxide.  Its  presence  in  condensed  milk,  therefore,  is  prone 
to  start  fermentation,  and  the  manufacturer  who  uses  it  with  a 
view  of  lessening  the  cost  of  manufacture  of  condensed  milk  is, 
indeed,  practicing  poor  economy.  There  is  no  adulteration  of 
sweetened  condensed  milk  that  will  produce  such  inevitable  disaster 
as  the  addition  to  it  of  glucose.  Aside  from  this  fact,  the  law  pro- 
hibits the  addition  of  anything  except  sucrose. 

Addition  of  Bi- Carbonate  of  Soda,  Ammonium  Hydroxide, 
Lime  Oxide  and  Lime  Hydrate  and  Other  Alkali. — These  alkalies 
and  alkaline  earths  are  frequently  added  to  a  poor  quality  of  fresh 
milk,  for  the  purpose  of  neutralizing  the  excess  of  acid  and  pre- 
venting the  milk  from  curdling  when  exposed  to  heat.  If  used 
in  reasonable  quantities,  they  interfere  in  no  way  with  the  quality 
and  healthfulness  of  the  product,  and  may  in  exceptional  cases  pre- 
vent great  loss.  If  used  in  excess,  the  milk  will  foam  very  badly 
in  the  vacuum  pan,  which  renders  the  process  of  condensing  a  diffi- 
cult one  and  the  finished  product  has  a  bitter  flavor.  Under  ordi- 
nary conditions,  their  use  is  entirely  unnecessary  and  simply  means 
additional  labor  and  expense.  The  above  agents  and  also  viscogen, 
are  sometimes  used  with  the  view  of  thickening  the  product  and  in- 
creasing the  output.  Experimental  results,1  however,  showed  that 
these  agents  cannot  be  used  in  large  enough  quantities  to  produce 
the  above  results  without  materially  lowering  the  quality  of  the 
product. 

Addition  of  Cream  of  Tartar. —  Cream  of  tartar  is  used  ex- 
tensively in  the  manufacture  of  candies  and  caramels.  Its  purpose 
is  to  make  the  sugar  in  these  products  precipitate  in  the  form  of 
very  fine  and  soft  crystals.  Condenseries,  which  have  been  con- 
tinually troubled  with  sugar  crystallization  and  sugar  sediment,  have 
tried  to  overcome  this  defect  by  adding  cream  of  tartar  to  the 
sweetened  milk  in  the  vacuum  pan.  Cream  of  tartar  is  an  acid 
salt  (acid  potassium  tartrate,  KH.C4H4O6),  and  it  is  this  acid 
which  in  the  manufacture  of  candy  causes  the  fine  and  soft  grain 
of  the  sugar.  It  is  obvious  that  if  enough  cream  of  tartar  were 
added  to  condensed  milk  to  produce  the  desired  effect  on  the  sugar, 


1  Hunziker.     Experiments  not  published. 


ADULTERATIONS  OF  CONDENSED  MILK  233 

the  acid  present  would  curdle  the  milk.     Its  use  is  of  no  value  to 
the  manufacturer  of  condensed  milk. 

Addition  of  Starch. —  The  pasty  and  thick  consistency  of 
sweetened  condensed  milk  frequently  suggests  to  the  public  that  it 
contains  starch.  This  is  erroneous,  for  it  is  doubtful  if  condensed 
milk  is  ever  adulterated  with  starch.  There  would  be  nothing 
gained  by  so  doing,  and  the  presence  of  starch  in  condensed  milk 
could  be  readily  detected  with  iodine.  Iodine  gives  the  starch  cells 
a  deep  blue  color. 


PART  VI. 
MANUFACTURE  OF  MILK  POWDER 

CHAPTER  XXVI. 
DEFINITION 

Milk  powder,  dry  milk,  pulverized  milk,  dehydrated  milk,  des- 
iccated milk,  is  made  from  cow's  whole  milk,  or  partly  or  wholly 
skimmed  milk,  to  which  sugar,  or  alkalies,  or  both  may,  or  may  not 
have  been  added,  and  which  has  been  evaporated  to  dryness,  either 
under  atmospheric  pressure,  or  in  vacuo. 

KINDS 

The  milk  powders  on  the  market  vary  chiefly  in  their  solubility 
and  fat  content.  The  bulk  of  the  milk  powders  is  produced  from 
wholly  or  partly  skimmed  milk.  Most  of  the  milk  powders  of  the 
early  days  of  this  industry  contained  added  cane  sugar  and  alkalies. 
The  purpose  of  the  addition  of  alkalies  was  to  lend  greater  solubility 
to  the  proteids. 

The  process  of  manufacture,  however,  has  been  improved  to 
the  extent  to  where  the  solubility  of  the  proteids  can  now  be  pre- 
served without  the  admixture  of  alkalies.  Most  of  the  milk  powders 
put  on  the  market  in  this  country  are  free  from  admixture  of  any 
substances  foreign  to  normal  milk. 

HISTORY  AND  DEVELOPMENT  OF  INDUSTRY 

The  origin  and  history  of  the  milk  powder  industry  are  very 
closely  related  and  intimately  connected  with  that  of  the  condensed 
milk  industry.  The  fundamental  purpose  of  the  two  products  is 
one  and  the  same,  i.  e.,  to  preserve  milk  as  nearly  as  possible  in  its 
natural  condition,  and  to  reduce  its  bulk  to  the  minimum,  so  as  to 
make  possible  its  economical  transportation  to  all  parts  of  the  world. 

The  difference  between  milk  powder  and  condensed  milk  is 
mainly  one  of  degree  of  concentration.  It  is  not  surprising,  there- 
fore, that  the  inventions  of  processes  of  manufacture  of  the  two 


MANUFACTURE:  OF  MILK  POWDER  235 

products  date  back  to  about  the  same  period,  the  middle  of  last 
century,  and  in  most  cases  the  inventors  of  the  one  product  had  also 
in  mind  and  gave  due  consideration  to  the  possibilities  of  the  other. 

The  first  commercially  usable  process  was  invented  by  Grim- 
wade  who  secured  the  English  patent  in  1855.  His  process  con- 
sisted briefly  of  first  adding  carbonate  of  soda  or  potash  to  the  fresh 
milk,  then  evaporating  in  open  jacketed  pans  and  with  constant 
agitation,  until  a  dough-like  substance  was  obtained;  then  adding 
cane  sugar;  the  mixture  was  then  pressed  between  rollers  into  rib- 
bons, further  dried  and  then  pulverized.  The  alkali,  in  the  form  of 
carbonate  of  soda  or  potash,  was  added  in  order  to  render  the  casein 
more  soluble,  and  the  purpose  of  the  admixture  of  the  sugar  was  to 
produce  granulation  of  the  dough  toward  the  end  of  the  process. 
The  evaporation  in  open  pans  was  later  superseded  by  the  use  of 
the  vacuum  pan.  The  Grimwade  process  of  manufacturing  milk 
powder  was  in  practice  for  some  years. 

The  introduction  and  rapid  development  of  the  condensed  milk 
industry  and  the  difficulty  of  the  economic  manufacture  of  a  mar- 
ketable milk  powder  of  good  keeping  quality,  had  a  retarding  effect 
on  the  development  of  the  milk  powder  industry.  While  occasional 
new  processes  were  invented  and  new  patents  granted,  the  com- 
mercial development  of  the  industry  dates  back  only  to  the  closing 
years  of  the  nineteenth  century.  Within  the  last  decade  the  industry 
in  this  country  and  in  Europe  has  been  growing  rapidly.  Today 
there  are  in  operation  in  the  United  States  numerous  milk  powder 
factories. 

The  bulk  of  the  milk  powder  manufactured  now1  is  made  from 
skimmed  milk.  The  manufacture  of  whole  milk  powder  is  as  yet 
very  limited  and  is  confined  to  the  filling  of  specific  orders  for  the 
same,  because  of  its  low  keeping  quality.  The  fact  that  whole  milk 
powder  becomes  rancid  under  similar  conditions,  as  is  the  case  with 
butter,  and  that  it  must  be  refrigerated  in  order  to  keep,  is  over- 
shadowing the  many  and  distinct  advantages  of  this  concentrated 
product.  Until  this  obstacle  is  removed  and  the  manufacturer  is 
able  to  put  on  the  market  a  whole  milk  powder  that  has  the  desired 
keeping  properties,  the  development  of  this  industry  cannot  reach 
the  proportions  justifiable  by  the  great  usefulness  of  this  valuable 
product  and  comparable  with  the  manufacture  of  other  forms  of 
preserved  milk  and  dairy  products. 


236 


MANUFACTURE  OF  MILK  POWDER 


QUALITY  OF  FRESH  MILK 

What  has  been  stated  concerning  the  necessity  of  a  high  quality 
of  fresh  milk  in  the  successful  manufacture  of  condensed  milk,  is 
equally  true  in  the  manufacture  of  milk  powder.  The  fresh  milk 
must  be  normal  in  its  properties.  It  must  be  produced  under  strictly 
sanitary  conditions  and  receive  the  proper  care  on  the  farm.  It  is 
especially  essential  that  it  arrive  at  the  factory  perfectly  sweet,  since 
acidity  tends  to  lower  the  solubility  of  the  finished  product. 

DESCRIPTION  OF  THE  PRINCIPAL  PROCESSES  OF 
MANUFACTURE 

Numerous  processes  for  the  manufacture  of  milk  powder  have 
been  invented  and  patented  in  this  country  and  in  Europe.  Many 
of  these  processes  differ  but  slightly  from  one  another.  For  con- 
venience's sake  these  processes  are  herein  classified  in  accordance 
with  the  fundamental  principles  of  evaporation  involved : 

1.  The  Wimmer  Process. —  The  milk 
is  boiled  in  a  vacuum  pan  similar  to  that 
used  in  the  manufacture  of  condensed 
milk.  The  vacuum  pan  has  a  deep  steam 
jacket  for  heating,  but  in  the  place  of  the 
usual  coils,  the  pan  is  equipped  with  a 
mechanical  stirrer.  The  milk  is  con- 
densed at  a  relatively  low  temperature 
and  the  stirrer  revolves  until  the  water 
content  of  the  milk  is  reduced  to  about 
30  per  cent  and  the  milk  has  become 
porous  and  crumbly,  though  it  still  forms 
a  compact  mass.  The  drying  is  then  com- 
pleted in  the  open  air  and  without  addi- 
tional heating.  The  product  is  then 
ground  to  a  powder.  This  is  the  process 
invented  by  Ole  Bull  Wimmer  of  Copen- 
hagen, Denmark. 

2.  The  Just-Hatmaker  Process. — The  milk  sprays  in  a  thin 
film  over  two  steam  heated  cylinders  or  drums,  about  sixty  inches 
long  and  twenty-four  inches  in  diameter-  The  cylinders  are  about 


Fig.   58.      The   Wimmer  milk 
powder  machine 


MANUFACTURE:  OF  MII<K  POWDER  237 

one-eighth  of  one  inch  apart  and  revolve  in  opposite  directions. 
The  milk  reaches  the  drums  from  a  supply  tank  located  in  the  center 
above  the  drums.  In  order  to  insure  a  continuous  and  uniform 
supply  of  milk,  a  constant  level  of  about  four  inches  of  milk  is 
maintained  in  the  supply  tank.  This  process  was  invented  by  J.  R. 
Hatmaker  of  London,  and  was  patented  in  1902.  Its  objectionable 
feature  lies  in  the  fact  that  the  excessive  heat  at  which  the  milk  is 
evaporated  impairs  the  solubility  of  the  product.  The  cylinders  are 
charged  with  two  to  three  atmospheres  of  steam  pressure,  causing 


Fig.  59.     The  Just- Hatmaker  milk  drier 

the  heating  surface  to  have  a  temperature  of  about  250  to  280 
degrees  F. 

The  Ekenberg  Process.— This  process  was  invented  by  Martin 
Ekenberg,  of  Stockholm,  Sweden,  in  the  year  1899,  and  is  covered 
by  a  number  of  United  States  patents,  one  of  the  earlier  of  which 
is  patent  No.  764995,  issued  in  1904. 

The  Ekenberg  Exsiccator,  or  milk  drier,  consists  of  a  revolving, 
steam  heated  nickel  drum,  inclosed  in  a  vacuum  chamber.  The  ends 
of  the  drum  form  bell-shaped  bowls,  dished  outward.  The  drum 
is  equipped  with  knives  or  scrapers,  which  remove  the  film  of  dried 
milk  that  gathers  on  the  drum.  Attached  to  the  vacuum  chamber 
there  is  a  smaller  chamber  which  serves  to  receive  the  dried  milk 


238 


MANUFACTURE  OF  MILK  POWDER 


as  it  is  scraped  from  the  drum.  This  is  separated  from  the  large 
vacuum  chamber  by  a  series  of  air  locks,  so  that  the  material  may  be 
removed  without  breaking  the  vacuum  in  the  large  chamber. 

The  milk,  as  it  enters  the  vacuum  chamber,  is  sprayed  into  the 
concave  ends  of  the  drum.  In  this  manner  it  is  fore-condensed. 
It  is  then  withdrawn  from  the  vacuum  chamber  by  a  pump,  and 


Fig.  60.     The  Ekenberg  milk  drier 

returned  again,  this  time  being  sprayed  upon  the  periphery  of  the 
drum.  The  milk  remains  on  the  drum  only  long  enough  for  it  to 
make  three-quarters  of  a  revolution. 

After  the  dried  milk  is  removed  from  the  exsiccator,  it  is  placed 
in  a  special  drying  chamber  at  a  temperature  of  90  degrees  F.  where 
it  remains  long  enough  for  the  milk  sugar  to  crystallize.  This  is 
usually  accomplished  in  about  an  hour.  After  this  it  is  ground  and 
sifted  in  a  similar  manner  as  is  the  case  in  the  milling  of  wheat  flour. 


MANUFACTURE  OF  MILK  POWDER  239 

It  is  then  ready  for  the  market,  which  it  reaches  packed  in  either 
tins,  boxes,  or  barrels. 

The  fact  that  the  milk  is  evaporated  under  reduced  pressure 
makes  it  possible  to  accomplish  the  drying  at  a  relatively  low  tem- 
perature, although  the  film  of  drying  milk  is  naturally  exposed  for 
a  very  brief  time  to  the  direct  heat  of  the  drum,  and  which  obviously 
varies  with  the  steam  pressure  in  the  drum.  The  manufacturers 
claim  that  the  drying  of  the  milk  takes  place  at  a  temperature  of 
about  100  degrees  F.  and  that  the  milk  at  no  time  reaches  tem- 
peratures higher  than  120  degrees  F.  . 

The  Buflovak  Process. —  The  principle  of  drying  milk  and 
other  liquids  on  a  steam-  or  hot  water-heated  revolving  drum  has 
been  put  to  extensive  application  through  the  activities  of  the 
Buffalo  Foundry  &  Machine  Co.,  Buffalo,  N.  Y.  This  company 
has,  during  the  last  decade,  invented,  constructed  and  perfected  the 
"Buflovak"  vacuum  drum  drier.  Patents  were  granted  their  engi- 
neer, Mr.  O.  S.  Sleeper,  by  the  United  States  Government  in  1911, 
1913,  1914,  1915  and  1916.  All  these  patents  were  assigned  to  the 
Buffalo  Foundry  and  Machine  Co. 

These  patents  pertain  to  the  drum  drier  as  used  for  whole  milk, 
skim  milk,  buttermilk  and  milk  products  in  general.  They  are 
applicable  to  other  products  as  well  as  to  milk,  but  for  milk  they  are 
made  specially  accessible  for  cleaning  and  for  sanitary  control. 

The  Buflovak  drier  consists  of  a  casing  in  which  revolves  a 
steam-heated,  polished  drum.  The  milk  is  fed  to  the  surface  or 
periphery  of  this  drum  by  a  pan  located  beneath  the  drum  and 
placed  lightly  against  the  drum.  The  pan  has  an  overflow  along  one 
side  for  the  automatic  removal  of  the  surplus  milk  not  taken  up  by 
the  drum.  To  the  bottom  of  this  casing  is  supplied  a  quantity  of 
milk.  This  is  pumped  to  the  supply  pan  under  the  drum,  the 
overflowing  milk  running  back  into  the  lower  portion  of  the  casing. 
There  is  slight  pressure  in  the  supply  pan  which  causes  the  drum  to 
take  up  a  heavy  and  even  coating.  Near  the  supply  pan  is  installed 
a  leveling  arrangement  which  levels  off  and  equalizes  the  layer  of 
milk  on  the  drum.  As  the  drum  revolves  and  the  layer  of  milk 
reaches  what  is  termed  the  front  of  the  machine  it  is  continuously 
removed  in  the  form  of  a  dry  film  by  a  stationary  scraper.  At  this 
point  the  machine  is  provided  with  a  breaker  which  consists  of  a 
shaft  with  a  number  of  rods  projecting  through  the  same,  which 


240 


MANUFACTURE  OF  MILK  POWDER 


revolves  to  break  up  the  film  of  dried  milk  as  it  leaves  the  drum. 
This  does  not  reduce  the  film  to  a  powder,  but  causes  the  material 
to  be  sufficiently  broken  up  to  allow  it  to  fall  into  the  receiver  where 
it  can  be  easily  handled  for  removal. 


Fig.  61.     The  Buflovak  vacuum  drum  drier 
Courtesy   of   Buffalo  Foundry   &   Machine   Company 

The  receiver  is  a  large  cylindrical  pan  placed  below  the  scraper 
at  the  front  of  the  machine.  Observation  glasses  are  placed  so  that 
all  internal  parts  may  be  seen  while  being  operated.  The  receiver 
is  equipped  at  each  end  with  a  door  of  the  full  width  of  the  receiver, 
facilitating  the  rapid  removal  of  the  dried  milk. 

Aside  from  the  circulating  pump  for  supplying  the  milk  to  the 
feed  pan,  there  is  a  condenser  and  a  dry  vacuum  pump.  Before 
the  vapors  reach  the  condenser,  they  pass  through  a  dust  collector. 
This  is  water-sealed  and  prevents  the  accumulation  in  the  vapor 
pipe  of  any  dust  that  may  escape  from  the  drum  and  pass  to  the 
condenser. 


MANUFACTURE:  OF  MILK  POWDER 


241 


This  drier  is  operated  under  a  high  vacuum,  permitting  rapid 
evaporation  at  a  relatively  low  temperature.  The  actual  drying  time 
of  the  film  of  milk  on  the  drum  is  about  6  to  7  seconds.  The  opera- 
tion is  continuous  and  at  the  conclusion  of  the  day's  run  the  machine 
is  washed  out.  If  subsequently  closed  up  and  evacuated  for  a  few 
minutes,  the  entire  interior  will  be  dry  insuring  a  sanitary  .condition 
of  the  machine. 

4.  The  Campbell  Process. — A   current    of    warm    air    passes 
through  the  milk  upward  until  the  milk  has  become  thick.     The 
remainder  of  the  drying  is  accomplished  by  exposure  to  heated  air. 
The  dried  milk  is  then  ground  to  a  powder.     This  is  the  Campbell 
process,  invented  in  1900  and  patented  by  J.  H.  Campbell  of  New 
York  in  1902. 

5.  The  Merr ell- Gere  Process. —  The  milk  is  condensed  in  the 
vacuum  pan  to  about  one-third  to  one-fourth  its  volume.    The  con- 


Fig.  62.     The   Campbell   milk  drier 

I  A  concentrated  vessel,  a  outlet,  b  valve,  c  hot  water  jacket,  c1  hot 
water  pipe,  c2  discharge  of  jacket,  B  air  pipe,  e  connecting  hose,  f  stand  pipe, 
g  air-distributing  disc,  t  air  chamber. — II  E  pug  mill,  i  cylinder,  j  hopper, 
k  chute,  1  horizontal  shaft,  m  blades  for  stirring,  m'  projections  for  scraping 
blades,  F  Vermicelli-machine,  n  hopper,  o  cylindrical  chamber,  p  piston, 
q  spiral  screw,  q'  worm-wheel,  o'  small  holes,  r  endless  traveling  apron, 
s  tray  with  perforated  bottom. — III  G  drier,  t  body  of  drier,  H  blower,  t' 
flue,  u  opening  to  insert  trays,  u'  opening  for  removing  trays,  vv*  endless 
chains  with  projections  for  supporting  trays,  w  coil  heater,  w'  pipe  circu- 
lating hot  water. 


242 


MANUFACTURE:  OF  MILK  POWDER 


densed  but  still  fluid  milk  is  forced  under  pressure  through  a  fine 
jet,  causing  it  to  be  atomized  and  sprayed  into  a  current  of  hot  air, 
in  an  evaporating  chamber.  This  atomized  liquid  forming  a  mist 
offers  the  maximum  surface  for  evaporation  of  its  water.  The  hot 
air  absorbs  the  moisture  of  the  milk  almost  instantly  and  the  milk 
drops  to  the  bottom  of  the  chamber  in  the  form  of  a  snow-like  pow- 
der. No  grinding  is  necessary.  This  process  was  invented  by  L.  C. 
and  I.  S.  Merrell  and  W.  B.  Gere,  assignors  to  Merrell-Soule  Co., 
of  Syracuse,  N.  Y.,  and  patented  July  23,  1907.  The  following  are 
the  claims  of  the  patentees: 


Fig.  63.     The   Merrell-Gere  milk  drier 


1  intake  of  milk,  2  vacuum  pan,  3  jacket,  4  steam   intake  into  jacket, 
5  dome  of  pan,  6  vacuum  pumps,  7  condenser,  10  water  column,  11  overflow 


MANUFACTURE  OF  MILK  POWDER  243 

cistern  for  dry  vacuum  system,  12  discharge  pipe  of  pan,  13  pump,  14  pressure 
gauge,  15  thermometer,  16  sight-glass,  17  regulating  valve,  18  two-way  draw- 
off  cock  for  sampling,  19  reservoir,  21  desiccating  chamber,  22  spray  jet, 
23  force  pump,  24  air  pump,  25  compressed  air,  26  air  drying  chamber,  27  air 
heater,  28  stand-pipe,  29  drip  valve,  30  depository  of  part  of  powder,  31  outlet 
of  powder,  32  rotary  gate,  33  receptacle,  34  rotary  dust  collector  consisting 
of  tubular  screen  partitions,  35  openings  connecting  with  desiccating  chamber, 
36  head  closing  tubular  screen,  37  springs,  38  gear  for  rotating  dust  collector, 
39  receptacle,  40  screw  conveyor  removing  powder  into  41  which  is  a  chute, 
42  automatic  discharge  valve,  43  beater  to  remove  adhering  powder,  44  spring 
of  beater,  45  rod,  46  toothed  rack,  47  driving  shaft,  48  suction  pump  to 
facilitate  removal  of  powder,  49  conduit,  50  casing  inclosing  dust  collector, 
51  discharge  of  casing,  52,  53  and  54  terminal  branches,  55  rotary  valve,  56 
auxiliary  valve  conduit,  57  supplementary  valve  conduit,  58,  59,  61,  62,  63  and 
64  equipment  for  treating  either  colloids  or  crystalloids  separately. 

"CLAIMS  : 

1.  "The  process  of  obtaining  the  solid  constituents  of  liquids 
and  semi-liquids,  in  the  form  of  powder,  which  process  consists  in 
concentrating  the  substance  by  removing  a  large  percentage  of  the 
water  therefrom,  converting  the  concentrated  mass  into  a  fine  spray, 
bringing  such  spray  into  a  current  of   dry  air  or  gas  having  an 
avidity  for  moisture  so  that  substantially  all  the  remaining  liquid 
constituents  are  separated  thereby,  conveying  the  dry  powder  into 
a  suitable  collecting  space  away  from  the  air  or  gas  current,  and 
discharging  the  air  or  gas  separately  from  the  dry  powder. 

2.  "The  process  of  obtaining  the  solid  constituents  of  liquids 
and  semi-liquids,  in  the  form  of  powder,  which  process  consists  in 
concentrating   the   substance   by   removing   a   large   percentage   of 
water  therefrom,  converting  the  concentrated  mass  into  a  spray, 
bringing  such  spray  into  a  current  of  dry  heated  air  or  gas  having 
an  avidity  for  the  moisture  of  the  substance  treated,  retaining  the 
atoms  momentarily  in  said  current  so  that  substantially  all  the  re- 
maining moisture  is  converted  into  vapor  and  the  product  is  pre- 
vented by  the  cooling  effect  of  such  evaporation  from  undergoing 
chemical  change,  conveying  the  dry  powder  into  a  suitable  collecting 
space  away  from  the  vaporizing  current,  and  discharging  the  air  or 
gas  separately  from  the  dry  powder. 

"In  witness  whereof  we  have  hereunto  set  our  hands  this  7th 
day  of  August,  1906." 

LEWIS  C.  MERREU,. 
Witnesses :  IRVING  S.  MERRELI,. 

H.  E.  CHASE,  WIUJAM  B.  GERE. 

HOWARD  P.  DENISON." 


244  MANUFACTURE:  OF  MILK  POWDER 

In  the  above  classification  of  processes,  only  those  processes 
have  been  discussed  which  produce  true  milk  powders  without  the 
admixture  of  alkalies  or  sugar  and  which  are  commercially  prac- 
tical. Numerous  other  processes  have  been  patented,  especially  in 
European  countries.  Most  of  these  require  the  addition  to  the  milk 
of  either  alkalies,  or  sugar,  or  both,  or  else  their  application  has  not 
been  found  commercially  successful. 


MANUFACTURE:  OF  MILK  POWDER 


245 


CHAPTER  XXVII. 
PACKING  FOR  THE  MARKET 

The  dried  milk,  reduced  to  a  fine  powder,  is  put  on  the  market 
in  packages  of  various  types  and  sizes.  Small  packages  are  usually 
put  up  in  tin  or  fibre  cans  holding  from  eight  ounces  to  ten  pounds 
of  milk  powder.  These  cans  are  closed  with  a  friction  cap.  The 
bulk  of  dried  milk  is  put  up  in  barrels  which  are  lined  with  parch- 
m,ent  paper  similar  to  the  lining  of  sugar  barrels.  Milk  powder 
should  be  stored  in  a  dry  atmosphere.  When  exposed  to  dampness 
it  is  prone  to  absorb  moisture.  In  this  condition  its  life  is  short- 
ened, as  it  becomes  mouldy  and  spoils. 


COMPOSITION  OF  MILK  POWDER 

Milk  powder  is  made  from  whole  milk,  partly  skimmed  milk 
and  skim  milk.  The  following  figures  show  the  composition  of 
milk  powders  manufactured  by  the  several  different  processes. 


Composition  of  Milk  Powders  Manufactured  by  Different 
Processes. 


Process 

3|* 

fcftg 

Proteids 
per- 
cent. 

0> 

%.  *->•» 

2$fl 

<5  ft  a? 

3  ! 

Sucrose 
per- 
cent. 

A    fH-M 

GO  4>  £ 
<Jftg 

ui*+S 

s&g 

£  ° 

Whole  milk 

1Merrell  and  Gere 

29.20 

26.92 

36.48 

6.00 

1.40 

2J.  R.  Hatmaker 

21.70 

28.70 

35.10 

6.50 

8.00 

Half  skimmed 

1Merrell  and  Gere 

15.12 

33.30 

39.70 

6.90 

5.00 

2J.  R.  Hatmaker 

13.00 

30.57 

48.85 

7.28 

8.30 

Process  not  known 

15.80 

37.45 

33.11 

7.34 

6.30 

Skimmed 

1Merrell  and  Gere 

1.00 

37.00 

47.00 

8.00 

7.00 

J.  R.  Hatmaker 

1.00 

37.28 

46.30 

8.00 

7.40 

1  Larsen  and  White,  Milk  Technology. 

8  C.  Huyge,  La  poudre  du  lait,  Revue  g6ne"rale  du  lait,  Vol.  3,  No.  14,  1904. 


246  MANUFACTURE  OF  MII.K  POWDER 

DEFECTS  OF  MILK  POWDERS 

High  Water  Content. — In  order  to  insure  keeping  quality,  milk 
powders  must  be  as  free  from  moisture  as  possible.  Milk  powders 
are  not  sterile,  nor  are  they  supposed  to  contain  preservatives,  such 
as  sucrose  and  chemicals.  Their  only  safeguard  against  bacterial 
fermentation  and  spoiling  is  their  comparative  freedom  from  water. 
Unless  the  process  fulfills  this  requirement,  milk  powders  will  not 
keep  and  their  chief  virtue,  which  renders  them  most  valuable,  is 
forfeited. 

Insoluble  Milk  Powders. — If  milk  powders  are  to  take  the 
place  of  fresh  milk  or  condensed  milk  on  the  table  of  the  consumer, 
they  must  be  readily  soluble.  One  of  the  greatest  obstacles  in  the 
progress  of  the  milk  powder  industry  has  been  that  the  dried  milk 
of  most  of  the  processes  failed  to  be  readily  and  completely  soluble. 
Earlier  processes  prescribed  the  admixture  to  the  milk  of  alkalies 
in  order  to  preserve  the  solubility  of  the  proteids,  which  otherwise 
were  rendered  insoluble  by  the  high  heat  of  the  respective  pro- 
cesses. It  is  obvious  that  a  dried  milk,  the  solubility  of  which  can 
be  retained  only  by  the  admixture  of  alkalies,  is  a  poor  substitute 
for  milk,  and  the  very  principle  of  adding  chemicals  to  a  food  prod- 
uct like  milk,  is  contrary  to  our  ideal  of  honest  and  successful  man- 
ufacture of  high  quality  of  product.  In  the  most  approved  pro- 
cesses now  in  use,  the  milk  is  never  exposed  to  temperatures  high 
enough  to  render  the  proteids  of  the  resulting  milk  powder  in- 
soluble, and  in  their  applications  the  use  of  solvents  is  unnecessary. 

Non-miscible  Milk  Powders. — The  miscibility  of  the  dried 
milk  with  water  depends,  aside  from  its  solubility,  on  the  physical 
condition  of  its  butter  fat  and  the  casein.  If  the  process  employed 
is  such  as  to  destroy  the  globular  form  of  the  fat  globules,  it  is 
impossible  to  reduce  the  dried  milk  to  a  homogeneous  fluid,  similar 
to  normal  fresh  milk.  The  fat  in  such  milk  will  rise  to  the  surface 
quickly,  similar  to  the  fat  in  a  mixture  of  oil  and  water. 

In  fresh  and  normal  milk  the  casein  is  present,  not  in  solution, 
but  in  suspension.  The  particles  of  casein  are  very  minute  and 
form  an  intimate  mechanical  union  with  the  water.  In  this  condi- 
tion they  are  present  in  the  form  of  a  homogeneous  emulsion  with 
the  other  ingredients  of  the  milk.  When  the  milk  is  desiccated  at 
high  temperatures,  the  particles  of  casein  lose  their  property  of 


MANUFACTURE;  OF  MILK  POWDER  247 

emulsifying  and  when  the  desiccated  milk  is  redissolved,  the  casein 
fails  to  be  miscible,  dropping  to  the  bottom  in  the  form  of  finely 
divided,  insoluble  curd.  In  order  to  produce  milk  powder  which 
is  miscible  in  water,  the  process  and  heat  used  must  be  such  as  to 
permit  the  casein  to  pass  into  the  finished  product  in  its  natural  state. 

Rancid  Milk  Powder.— From  the  biological  point  of  view,  milk 
powder,  properly  made  and  with  a  minimum  moisture  content, 
cannot  decompose.  Unfortunately,  one  of  the  constituents  of  dried 
milk,  the  butter  fat,  is  prone  to  undergo  chemical  changes  upon 
exposure  to  light,  heat  and  air.  The  less  stable  fatty  acids  evidently 
yield  to  chemical  disintegration,  giving  the  product  a  rancid  and 
tallowy  flavor.  Experimental  data  showing  the  exact  action  that  is 
responsible  for  this  deterioration  are  not  available.  It  is  not  improb- 
able that  both,  hydrolysis  and  oxidation  enter  into  this  problem.  Even 
the  most  experienced  manufacturers  of  milk  powder,  using  the 
most  perfected  processes  now  known,  admit  that  milk  powder  made 
from  whole  milk,  or  partly  skimmed  milk,  will  become  rancid  when 
exposed  to  air,  light  and  ordinary  temperatures. 

Experience  has  amply  demonstrated  that  whole  milk  powder 
will  deteriorate  and  become  rancid  and  tallowy  very  much  under 
the  same  conditions  as  butter.  In  order  to  prevent  whole  milk  pow- 
der from  becoming  rancid,  it  must  be  stored  in  the  cold. 

MARKETS 

Owing  to  its  relatively  poor  keeping  quality,  the  markets  for 
whole  milk  powder  are  limited.  It  is  a  most  ideal  substitute  for 
fresh  milk  or  condensed  milk,  if  used  when  fresh  or  whenever,  in 
its  storage  and  transportation,  it  can  be  protected  by  cold.  This 
requirement,  however,  is  a  serious  obstacle  to  its  omni-usefulness 
and  will  remain  a  hindrance  to  its  introduction  in  the  pantry  of  the 
consumer,  until  the  manufacturer  succeeds  in  correcting  this  defect. 

Skim  milk  powder,  on  the  other  hand,  is  free  from  this  draw- 
back, and  when  properly  made  and  kept  dry,  it  keeps  indefinitely. 
It  has  become  a  most  valuable  dairy  product  and  its  uses  are  mani- 
fold. It  is  used  in  the  consumer's  kitchen,  in  bakeries  and  confec- 
tioners' establishments,  in  the  manufacture  of  ice  cream,  fermented 
milk  beverages,  and  starters  for  cream  ripening  where  milk  and 


248  DRIED  BUTTERMILK  AND  DRIED  WHEY 

skim  milk  are  not  available ;  in  the  preparation  of  baking  powder, 
of  pure  lactic  acid  cultures  for  creameries  and  cheese  factories,  of 
drugs,  choice  toilet  soaps,  etc.  In  European  countries  the  chocolate 
factories  purchase  vast  quantities  of  skim  milk  powder  in  the  manu- 
facture of  milk  chocolate  and  allied  products,  and  manufacturers 
of  diverse  prepared  food  products,  such  as  cereals,  soups,  noodles, 
and  vegetables,  furnish  additional  markets  for  this  new  dairy  prod- 
uct. 

Commercial  Stocks  of  Dried  Milk.1 — Commercial  stocks  of 
milk  powder  as  reported  in  the  Food  Surveys  of  January  1,  1918, 
amounted  to  13,296,422  pounds.  Of  this  total  the  ice  cream  manu- 
facturers held  19.1  per  cent;  warehouses,  19.4  per  cent;  wholesale 
dealers,  14.8  per  cent;  bakers,  13.3  per  cent,  and  retail  dealers,  1.9 
per  cent.  The  remainder,  amounting  to  31.5  per  cent  of  the  total, 
was  held  by  a  miscellaneous  group  of  concerns,  such  as  cheese  fac- 
tories holding  1,327,459  pounds;  creameries,  712,020  pounds;  con- 
fectioners, 621,428  pounds;  ice  cream  manufacturers,  569,249 
pounds,  and  other  miscellaneous  classes  929,289  pounds. 

CHAPTER  XXVIII. 
DRIED  BUTTERMILK  AND  DRIED  WHEY 

These  by-products  of  the  creamery  and  cheese  factory  can  be 
reduced  to  a  powder  in  a  similar  way  and  by  the  same  processes 
and  machinery  as  are  used  in  the  manufacture  of  dried  milk  and 
dried  skim  milk. 

Dried  buttermilk  makes  a  splendid  chicken  feed,  both  for  egg 
production  and  for  fattening  chickens.  It  is  best  diluted  to  about 
the  original  buttermilk  (one  part  powder  in  ten  parts  water)  and 
mixed  with  the  grain  feed  into  a  mush.  Like  fresh  buttermilk,  so 
is  dried  buttermilk  a  wholesome,  nutritious  and  easily  digested  food 
and  recommends  itself  especially  to  persons  with  weak  digestion. 
When  properly  made,  buttermilk  powder  keeps  indefinitely  and  may, 
therefore,  be  available  for  immediate  use  at  all  times. 

The  following  analyses  show  the  composition  of  buttermilk 
powder  and  of  the  fresh  buttermilk  from  which  it  was  made: 


1  Food   Surveys,   Bureau  of  Markets,   U.    S.   Dept.   Agriculture,   Volume   I, 
No.  7.     Special  Isslue,  June,   1918. 


DRIED  BUTTERMILK  AND  DRIED  WHEY  249 

COMPOSITION  OF  BUTTERMILK  POWDER. 

Fresh  buttermilk  Buttermilk  powder 

Butter  fat  1.17  per  cent  11.70  per  cent 

Proteids  3.00  per  cent  36.24  per  cent 

Lactose  2.97  per  cent  35.50  per  cent 

Ash  .85  per  cent  8.25  per  cent 

Acidity  .60  per  cent  6.00  per  cent 

Iron  (Fe2O3)  .00  per  cent  1.92  per  cent 

Water  91.63  per  cent  4.32  per  cent 

Total  100.22  per  cent  103.93  per  cent 

1  The  buttermilk  of  which  the  composition  is  shown  in  the  above 
table  was  made  at  the  plant  of  the  Buffalo  Foundry  and  Machine 
Company,  Buffalo,  N.  Y.,  under  the  supervision  of  the  writer.  The 
machine  used  was  of  the  Buflovak  type.  The  buttermilk  was  fur- 
nished by  Schlosser  Bros.,  of  Frankfort,  Indiana.  This  batch  of 
buttermilk  happened  to  be  abnormally  high  in  butter  fat;  therefore 
the  large  butter  fat  content  of  the  finished  product.  The  iron  found 
in  the  dried  buttermilk  is  probably  due  to  the  fact  that  the  drying 
drum  of  the  desiccator  was  of  iron  and  was  acted  upon  by  the  high 
per  cent  of  lactic  acid.  About,  thirty  pounds  of  steam  pressure  were 
used  in  the  drying  drum,  the  temperature  in  the  vacuum  chamber 
was  125  degrees  F.  and  the  vacuum  twenty-five  to  twenty-six  inches 
of  the  mercury  column. 

This  buttermilk  powder  had  a  nice,  clean,  acid  taste,  it  was 
much  relished  by  all  who  sampled  it  and,  when  fed  to  chickens  for 
fattening,  produced  satisfactory  gains  in  weight. 

Whey  powder  is  manufactured  in  a  similar  manner.  Its  chief 
value  lies  in  its  usefulness  in  the  diet  of  infants  and  invalids,  with 
whom  the  consumption  of  casein  produces  digestive  disturbances- 
Since  fresh  whey  is  often  not  obtainable,  the  whey  powder,  the  good 
keeping  quality  of  which  permits  of  keeping  it  on  hand,  furnishes 
an  admirable  substitute.  When  made  from  sour  whey,  it  offers 
many  advantages  in  cooking  and  baking  and  should  be  especially 
well  suited  for  such  dishes  as  pan  cakes,  etc. 

The  chief  objection  to  these  desiccated  dairy  by-products,  such 


1  Hunziker,  Indiana  Agricultural  Experiment  Station,  Twenty-sixth  Annual 
Report,   1913. 


250 

as  dried  skim  milk,  dried  buttermilk  and  dried  whey,  is  that  the 
cost  of  reducing  them  to  dry  ness  is  somewhat  out  of  proportion 
with  their  actual  market  value,  as  compared  with  the  raw  or  con- 
densed product.  Dried  skim  milk,  for  instance,  sells  at  13  to  14 
cents  per  pound.  When  diluted  to  the  consistency  of  the  raw  skim 
milk,  one  pound  of  powder  yields  about  ten  or  eleven  pounds  of 
skim  milk,  costing  between  $1.25  to  $1.40  per  hundred  pounds,  which 
is  almost  the  price  of  fresh  whole  milk.  It  is  obvious  that  the  aver- 
age creamery  cannot  afford  to  make  starter  at  the  rate  of  $1.25  to 
$1.40  per  hundred  pounds. 

For  the  same  reason  the  demand  for  dried  buttermilk  and  dried 
whey  is  as  yet  very  limited.  These  products,  in  their  natural  state, 
contain  too  small  a  proportion  of  the  valuable  ingredients,  and  they 
are  too  cheap  to  justify  the  high  cost  of  manufacture,  in  order  to 
place  them  on  the  market  in  the  dry  form.  This,  of  course,  does 
not  apply  to  the  use  of  dried  skim  milk  for  the  many  industrial  pur- 
poses mentioned,  where  properties  other  than  the  mere  food  value 
determine  the  real  merits,  value  and  usefulness  of  the  product. 

The  above  figures  and  statements  refer  to  conditions  prior  to 
the  world  war.  The  great  need  of  food  products  and  the  wave  of 
conservation  that  has  been  accentuated  by  the  drain  on  the  food 
supply  of  the  world,  resulting  from  the  destruction,  waste  and  stop- 
page of  production  in  the  warring  countries,  has  given  the  utiliza- 
tion of  these  valuable  by-products  a  new  impetus,  and  their  manu- 
facture into  marketable  and  transportable  commodities  promises 
rapid  development  for  the  benefit  of  mankind. 

MALTED  MILK1 

Definition. —  The  product  known  as  malted  milk  is  that  result- 
ing from  the  combination  of  whole  milk  with  the  extract  of  malted 
barley  and  wheat  flour,  and  the  mixture  is  reduced  to  a  dry  form  by 
desiccation  in  vacuo. 

History  of  Malted  Milk  Industry.— The  process  of  the  manu- 
facture of  malted  milk  was  invented  by  Mr.  William  Horlick,  of 
Racine,  Wis.,  in  the  year  of  1883.  The  product  was  first  placed  on 
the  market  under  the  name  of  "Malted  Milk,"  given  it  by  its  in- 
ventor, in  1887. 


1  Information   on  Definition,  History  and  Process   of  Manufacture,   received 
through  the  courtesy  of  Horlick's  Malted  Milk  Co.,  Racine,  Wis.,  March  8,  1918. 


MAI/TED  MILK  251 

The  convenience,  nutritive  value  and  digestibility  of  this  prod- 
uct recommended  themselves  to  and  were  appreciated  by  the  medical 
profession,  and  its  relishing  properties  appealed  to  the  public.  The 
industry  grew  rapidly  and  is  today  assuming  large  proportions. 


Fig.  64.    Vacuum  pan  for  malted  milk 
Courtesy  of  Arthur  Harris  &   Co. 

Manufacture  of  Malted  Milk.— A  mash  is  prepared  by  mixing 
wheat  flour  with  barley  malt  of  good  diastatic  quality.  This  mash 
is  raised  to  the  proper  temperature  for  a  sufficient  length  of  time  to 
insure  the  complete  conversion  of  the  insoluble  starch  into  the  solu- 
ble malt  sugars  dextrin  and  maltose.  This  conversion  is  closely  akin 
to  starch  digestion  in  the  human  system,  hence  the  resulting  liquid 
is  essentially  a  predigested  product,  claimed  to  be  of  much  value 
as  a  special  food  for  infants  and  invalids. 

This  extract  is  combined  with  whole  milk  and  reduced  to  a  dry 
powder  in  a  vacuum  at  such  a  low  temperature  as  will  thoroughly 
pasteurize  the  malted  milk  and  yet  preserve  its  digestibility. 


252  MAI/TED 

Uses  of  Malted  Milk. —  Malted  milk  is  the  only  milk  powder 
made  from  whole  milk  that  will  keep  indefinitely  in  any  climate.  It, 
therefore,  combines  with  its  acknowledged  high  degree  of  nutrition, 
the  indispensible  growth-promoting  and  curative  properties  con- 
tained in  whole  milk. 

It  is  placed  on  the  market  both  in  powder  and  in  tablet  form. 
Its  high  digestibility,  nutritive  value  and  health-protective  properties 
render  it  most  valuable  as  a  wholesome  food  for  infants  and  inva- 
lids, and  its  compactness  and  keeping  quality  facilitate  its  transpor- 
tation to  and  use  in  all  parts  of  the  globe.  Malted  milk,  therefore, 
is  of  special  merit  for  use  in  countries  and  territories  which  are 
barred  by  their  geographical  location  and  climate  from  the  profitable 
husbandry  of  the  dairy  cow,  and  where  the  limitations  of  transpor- 
tation render  the  availability  of  fluid  milk  difficult  or  impossible. 

Federal  Standards  for  Milk  Powder,  Skim  Milk  Powder  and 
Malted  Milk.1 — The  following  standards  of  dried  milk  products 
were  adopted  by  the  United  States  Department  of  Agriculture 
March  16,  1917,  and  became  effective  March  31,  1917,  as  per  Food 
Inspection  Decision  170: 

"DRIED  MILK  is  the  product  resulting  from  the  removal  of  water 
from  milk,  and  contains,  all  tolerances  being  allowed  for,  not  less 
than  twenty-six  per  cent  (26%)  of  milk  fat,  and  not  more  than  five 
per  cent  (5%)  of  moisture. 

DRIED  SKIMMED  MILK  is  the  product  resulting  from  the  removal 
of  water  from  skimmed  milk  and  contains,  all  tolerances  being  al- 
lowed for,  not  more  than  five  per  cent  (5%)  of  moisture. 

MALTED  MILK  is  the  product  made  by  combining  whole  milk 
with  the  liquid  separated  from  a  mash  of  ground  barley  malt  and 
wheat  flour,  with  or  without  the  addition  of  sodium  chlorid,  sodium 
bicarbonate  and  potassium  bicarbonate  in  such  a  manner  as  to  secure 
the  full  enzymic  action  of  the  malt  extract  and  by  removing  water. 
The  resulting  product  contains  not  less  than  seven  and  one-half  per 
cent  (7.5%)  of  butter  fat  and  not  more  than  three  and  one-half  per 
cent  (3.5%;)  of  moisture." 


1  United   States   Department  of  Agriculture,   Food   Inspection   Decision   170, 
March  31,  1917. 


PART  VII. 

STANDARIZATION,    TESTS    AND    ANALYSES 

OF  MILK,  CONDENSED  MILK  AND 

MILK  POWDER 

CHAPTER  XXIX. 

STANDARDIZATION 

Prior  to  the  enactment  of  the  Federal  Food  and  Drugs  Act, 
which  became  effective  January  1,  1907,  the  milk  condensing  fac- 
tories made  no  special  effort  to  place  on  the  market  a  product  of 
any  definite  and  specific  composition.  The  milk  was  condensed, 
either  as  whole  milk,  no  matter  what  the  original  composition  of 
the  fluid  milk  was,  without  modification,  or  it  was  partly  skimmed 
or  wholly  skimmed,  before  condensing.  If  any  effort  towards 
modification  of  the  composition  was  made,  such  effort  was  prac- 
tically wholly  confined  to  the  regulation  of  the  fat  content  of  the 
finished  product  and  even  in  such  cases  wide  fluctuations  were  quite 
frequent. 

With  the  enforcement  of  the  Federal  Food  and  Drugs  Act, 
the  milk  condenseries  found  themselves  called  upon  to  manufacture 
a  product  that  would  comply  with  the  Federal  standards  established 
and  which  prescribed  the  minimum  per  cent  of  fat  and  milk  solids 
permissible  in  condensed  milk.  • 

.It  became  necessary  therefore  to  guard  against  the  production 
of  condensed  milk,  the  per  cent  fat  and  milk  solids  of  which  fell 
below  the  specified  standard-  And  later,  with  the  rapid  develop- 
ment of  the  condensed  milk  industry,  competition  gradually  com- 
pelled the  individual  concerns  to  not  only  avoid  the  manufacture 
of  an  illegal  product  by  causing  its  valuable  components  to  fall  short 
of  the  percentage  required  by  the  standard,  but  to  so  modify  the 
composition  as  to  not  have  the  finished  product  materially  exceed 
the  required  standard,  in  order  to  keep  down  the  cost  of  manu- 
facture. Furthermore,  in  the  case  of  bulk  condensed  milk,  which 
goes  to  confectioners  and  ice  cream  manufacturers,  the  buyer  often 
specifies  in  his  order  the  desired  composition  of  the  product,  neces- 
sitating standardization  to  meet  these  special  demands. 


254  STANDARDIZING  COND£NS£D  MILK 

These  factors  and  conditions  inevitably  led  to  the  adoption  of 
the  practice  of  carefully  standardizing  condensed  milk  for  fat  and 
milk  solids.  The  details  of  methods  used  for  standardizing  vary 
considerably  with  different  manufacturers.  The  principle  upon 
which  standardization  is  based,  however,  is  obviously  very  much  the 
same  under  all  conditions,  and  variations  in  details  affect  the  results 
largely  only  with  reference  to  the  degree  of  accuracy. 

Some  manufacturers  standardize  the  fluid  milk  before  con- 
densing, others  prefer  to  standardize  after  evaporation  only,  while 
still  others  standardize  both,  the  fluid  milk  and  then  again  the 
finished  product  just  prior  to  canning.  Each  of  the  three  methods 
is  practical  and  the  double  method  of  standardizing  before  and  after 
condensation  is  obviously  the  most  exact.  In  the  case  of  sweetened 
condensed  milk  standardization  before  condensation  is  preferable 
inasmuch  as  the  admixture  to  the  finished  product  of  water,  skim 
milk  or  cream  is  not  advisable  from  the  standpoint  of  keeping 
quality,  unless  these  products  have  been  previously  properly  pas- 
teurized. In  the  case  of  evaporated  milk,  which  is  much  thinner, 
more  miscible  and  which  is  subsequently  sterilized,  these  objections 
are  largely  removed. 

The  materials  generally  used  for  standardizing  are  skim  milk, 
condensed  skim  milk,  cream,  butter  and  water.  Water  is  used  only 
to  lower  the  per  cent  total  solids,  or  the  degree  of  concentration,  and 
is  of  service  only  after  condensation  of  the  milk. 

The  calculations  employed  for  standardization  are  identical  for 
all  forms  of  condensed  milk  and  milk  powder,  both  sweetened  and 
unsweetened.  The  addition  of  cane  sugar  to  the  fluid  milk  does  .not 
alter  the  ratio  of  fat  to  milk  solids,  since  the  added  sugar  merely 
displaces  a  portion  of  the  water  in  the  finished  product. 

The  per  cent  total  solids  in  the  condensed  milk  is  controlled 
primarily  by  the  degree  of  concentration  as  determined  by  the 
Beaume  hydrometer  or  by  gravimetric  analysis  and  it  may  be  further 
modified  by  the  addition  of  water  to  the  finished  product  in  case 
condensation  has  passed  beyond  the  desired  point. 

Aside  from  this,  the  fundamental  effort  of  standardization  is 
confined  to  securing  the  desired  proportion  of  butter  fat  to  milk 
solids  not  fat-  When  this  is  accomplished  all  that  is  necessary  to 
insure  the  required  composition  is  to  subject  the  product  to  the 
necessary  degree  of  concentration. 


STANDARDIZING  CONDENSED  MILK 


255 


Standardizing  the  Fluid  Milk. — In  order  to  properly  stand- 
ardize the  fluid  milk  it  is  necessary  to  know  the  required  per  cent 
fat  and  solids  not  fat  in  the  finished  product  and  the  per  cent  fat 
and  solids  not  fat  in  the  milk  to  be  standardized  and  then  to  calcu- 
late the  proportion  of  fat  and  solids  not  fat  needed  in  the  fluid  milk. 
This  calculation  is  most  conveniently  made  by  allegation.  This  then 
shows  the  amount  of  fat  or  solids  not  fat,  as  the  case  may  be,  that 
must  be  added  to  secure  the  desired  proportion  of  these  ingredients 
and  from  this  the  amount  of  cream,  or  butter,  or  skim  milk  that 
must  be  used  for  standardizing  can  be  readily  determined. 

EXAMPLE  1. 

The  standard  for  evaporated  milk  is  7.8  per  cent  fat  and  25.5 
per  cent  total  solids,  or  (25.5  —  7.8)  =  17.7  per  cent  solids  not  fat. 
Amount  fluid  milk  in  batch,  7,000  pounds. 
Fat  in  fluid  milk,  3.3  per  cent. 
Solids  not  fat  in  milk,  9.0  per  cent. 
Fat  wanted  in  evaporated  milk,  7.8  per  cent. 
Solids  not  fat  wanted  in  evaporated  milk,  17.7  per  cent. 
What  per  cent  fat  should  fluid  milk  contain? 
How  much  cream,  testing  25  per  cent  fat,  must  be  added? 
Answer:     s.  n.  f.  in  c.  m-    :  s.  n.  f.  in  r.  m.  —  f.  in  c.  m.   :  X  I 
X  —  %  f.  required  in  r.  m- 

s.  n.  f .  — •  solids   not    fat. 

f.  =  fat. 

c.  m.       —  condensed  milk. 

r.  m.       =  raw   or   fluid   milk. 

17.7   :  9.  =z  7.8  :  X  ;  X  =  3.966%  fat. 

The  raw  milk  must  contain  3.966%  fat. 

How  much  25%  cream  is  required  to  raise  the  per  cent  fat  in 
the  7,000  pounds  of  milk  testing  3.3%  fat  to  3.966%  ? 

3.3  21.04 


3.96 


25. 


256 


STANDARDIZING  CONDENSED  MILK 


Enough  25%'  cream  must  be  added  to  the  raw  milk  so  that  each 
21.7  pounds  of  standardized  milk  contains  .66  pounds  of  added 
cream  and  21 .04  pounds  of  the  original  milk.  Hence  21 .7  :  .66  = 
7000  :  X  ;  X  —213.  Ibs.  of  cream. 

Total  batch,  7000  pounds. 
25%  cream,  213  pounds. 
3.3%  milk,  6787  pounds. 

EXAMPLE:  2. 

Amount  of  fluid  milk  in  batch,  7,000  pounds. 

Fat  in  fluid  milk,  4.5  per  cent. 

Solids  not  fat  in  fluid  milk,  8.5  per  cent. 

Fat  wanted  in  evaporated  milk,  7.8  per  cent. 

Solids  not  fat  wanted  in  evaporated  milk,  17.7  per  cent. 


How  much  fat  should  fluid  milk  contain? 
milk  must  be  added? 


How  much  skim 


Answer:     17.7  :  8.5  =  7.8  =  X  ;  X  =  3.75%.    The  fluid 
milk  must  contain  3.75%:  fat. 

How  much  skim  milk  must  be  added  to  lower  the  per  cent  fat 
in  the  fluid  milk  to  3.75%? 


4.5 


3.75 


.0 


3.75 


.75 


4.50 

Enough  skim  milk  must  be  added  to  the  fluid  milk  so  that  each 
4.5  pounds  of  standardized  milk  contains  .75  pounds  of  added  skim 
milk  and  3 . 75  pounds  of  original  milk.  Hence  4.50  :  .75  =  7000 
:  X  J  X  —  1167  pounds  of  skim  milk. 

Total  batch,  7000  pounds. 
Skim  milk,     1167  pounds. 

4.5%  milk,     5833  pounds. 


STANDARDIZING  CONDENSED  MILK 


257 


Standardization  of  Finished  Product.— In  a  similar  manner 
standardization  may  be  accomplished  after  condensation.  In  this 
case  the  proportion  of  solids  is  best  increased  or  the  proportion  of 
fat  reduced  by  the  addition  of  condensed  skim  milk  in  the  place  of 
ordinary  skim  milk,  while  the  proportion  of  fat  is  increased  by  the 
addition  of  cream  as  explained  under  Standardization  of  Fluid  Milk. 

If  it  is  desired  to  lower  the  total  solids  in  the  finished  product, 
without  affecting  the  proportion  of  solids  not  fat  to  fat,  the  neces- 
sary amount  of  water  required  is  determined  as  follows: 

EXAMPLE:. 

Evaporated  milk  in  batch,  3000  pounds. 
Total  solids  in  evaporated  milk,  27.%. 
Total  solids  desired,  25.5%, 
How  much  water  must  be  added? 
Answer : 

27. 


25.5 


0 


25.5 


1.5 


To  each  25 . 5  pounds  evaporated  milk  must  be  added  1 . 5  pounds 
water.  Hence  25.5  :  1.5  =  3000  :  X;  X  =  176.5  pounds  of 
water. 

Original  batch  evaporated  milk,  3000       pounds. 
Water  added,  176.5  pounds- 


Standardized  evaporated  milk,        3176.5  pounds. 

The  results  of  standardization  in  which  cream  is  used  to  alter 
the  proportion  of  fat  to  solids  not  fat,  are  not  absolutely  mathematic- 
ally accurate,  because  of  the  fact  that  the  per  cent  of  solids  not  fat 
in  the  cream  is  somewhat  lower  than  in  milk.  This  causes  a  slight 
shortage  of  solids  not  fat  in  the  standardized  product.  This  error 
is  so  slight,  however,  that  it  may  be  considered  within  the  limits  of 
the  experimental  error  and  for  all  practical  purposes  this  method 
of  standardization  may  be  accepted  as  reliable  and  accurate. 


258  CHEMICAL  TESTS  AND  ANALYSES 

CHAPTER  XXX. 

PRACTICAL  METHODS  OF  SYSTEMATIC  EXAMINATION 
OF  PRODUCT  FOR  MARKETABLE  PROPERTIES 

The  manufacturer  should  know  at  all  times  the  quality  and 
keeping  quality  of  his  product.  He  should  have  a  systematic  check, 
not  only  on  his  product  stored  in  the  factory,  but  also  on  the  goods 
in  transit  and  on  the  market,  in  order  to  promptly  detect  goods  that 
show  signs  of  deterioration.  This  will  enable  him  to  investigate  the 
cause  of  the  defect,  to  prevent  its  recurrence  and  to  avoid  spoiled 
goods  from  reaching  the  consumer.  The  following  simple  method 
of  systematic  examination  has  been  found  effective  in  keeping  a  re- 
liable check  on  each  batch  until  the  product  is  old  enough  to  have 
proved  its  immunity  from  the  usual  specific  defects. 

Number  of  Samples  Needed. —  Five  cans  of  every  batch  of 
condensed  milk  or  evaporated  milk,  bearing  the  corresponding  batch 
number,  are  reserved  for  this  purpose.  For  convenience's  sake  these 
sample  cans  are  best  stored  on  shelves  about  fifteen  inches  wide  and 
five  inches  apart.  These  dimensions  are  sufficient  to  conveniently 
accommodate  five  16-ounce  cans  of  one  and  the  same  batch  and 
placed  in  a  row,  one  behind  the  other.  These  shelves  should  be  in- 
stalled in  a  place,  preferably  the  office,  where  the  cans  may  be  ex- 
posed to  similar  changes  and  extremes  of  temperature,  as  is  the  case 
in  transit  and  in  the  retail  store.  The  cans  of  sweetened  condensed 
milk  should  be  placed  on  these  shelves  bottom-side  up.  The  cans 
of  evaporated  milk  should  be  placed  on  the  shelves  right-side  up. 

Frequency  of  Examination. — Every  day  one  can  of  condensed 
milk  or  other  product,  one,  three,  ten,  thirty  and  sixty  days  old,  re- 
spectively, is  opened  and  the  contents  are  carefully  examined  for 
thickness,  smoothness,  sugar  sediment,  curdiness,  fat  separation, 
color,  flavor,  fermentation  changes,  etc. 

Technique  of  Examination. —  Since  the  temperature  of  the 
product  influences  its  apparent  thickness,  it  is  desirable  to  examine 
the  condensed  milk  at  a  uniform  temperature,  preferably  60  or  70 
degrees  F.  This  is  best  accomplished  by  the  use  of  a  water-tight 
tray  of  galvanized  iron  or  tin,  about  twelve  inches  long,  nine  inches 
wide  and  three  and  one-half  inches  deep,  with  an  overflow  about 


CHEMICAL  TESTS  AND  ANALYSES  259 

two  and  one-half  inches  above  the  bottom.  Every  day  at  a  regular 
hour  the  samples  of  the  ages  above  stated  are  placed  into  this  tray, 
containing  water  at  the  desired  temperature  (60  to  70  degrees  F.), 
about  thirty  minutes  before  the  cans  are  opened.  All  cans  should 
be  placed  in  the  tray  right-side  up. 

Upon  opening  the  cans,  the  coating  on  the  lid  shows  the  pres- 
ence of  sugar  sediment  and  of  lumps  of  curd  in  the  case  of  sweet- 
ened condensed  milk,  and  a  layer  of  thick  and  buttery  cream  in  the 
case  of  evaporated  milk.  A  perfectly  clear  lid,  without  any  coating, 
indicates  the  freedom  of  the  product  from  these  defects.  In  the 
case  of  fermented  milk  the  ends  of  the  cans  are  usually  bulged. 
Upon  opening,  a  part  of  the  contents  is  forced  out.  The  thickness 
is  estimated  by  inserting  a  spatula,  or  spoon,  or  by  pouring,  and  the 
flavor  and  smoothness  are  determined  by  tasting. 

The  observations  should  be  carefully  recorded  in  a  book  re- 
served for  this  purpose,  and  any  changes  observed  as  the  milk  ad- 
vances in  age  should  be  noted. 

Interpretation  of  Results. — Most  of  the  physical  and  mechan- 
ical defects  appear  in  milk  from  one  to  ten  days  old.  Defects  re- 
sulting from  fermentation  processes  generally  become  noticeable 
two  to  three  weeks  after  manufacture. 

Fluctuations  in  the  thickness,  from  batch  to  batch,  indicate  lack 
of  proper  attention  on  the  part  of  the  pan-man  to  the  "striking"  of 
the  batches.  Sugar  sediment  shows  the  need  of  closer  attention  to 
the  solution  of  sucrose  and  the  cooling  of  the  condensed  milk. 
Lumps  and  buttons  suggest  the  acceptance  of  a  poor  quality  of 
fresh  milk,  or  unsanitary  condition  of  milk  cans,  vats,  pipes  and 
conveyors  in  the  factory,  or  unclean  tin  cans.  Fat  separation  and 
curdiness  of  evaporated  milk  suggest  a  faulty  process.  Fermenta- 
tion of  sweetened  condensed  milk  urges  investigation  of  the  quality 
and  condition  of  the  sugar  and  of  the  sanitary  condition  of  all  ap- 
paratus and  conveyors  of  milk,  condensed  milk  and  sugar,  from  the 
forewarmers  to  the  sealing  machine.  Fermented  evaporated  milk 
points  to  incomplete  sterilization  or  leaky  tin  cans,  etc. 

Systematic  Examination  a  Necessary  Feature  of  Economic 
Manufacture. — Manufacturers  who  neglect  to  conduct  a  systematic 
examination  of  their  product  similar  to  that  outlined  above  fre- 


260  CHEMICAL,  TESTS  AND  ANALYSES 

quently  argue  that  they  cannot  afford  to  waste  five  cans  out  of  every 
batch. 

This  is  indeed  a  mistaken  conception  of  economy.  With  the 
exception  of  fermented  milk,  the  "cut-opens"  can  be  emptied  into 
the  succeeding  batch,  so  that  all  that  is  lost  is  the  tin  cans.  Fer- 
mented goods  cannot  be  utilized  anyway,  neither  on  the  market  nor 
elsewhere.  Their  loss,  therefore,  will  occur  whether  in  the  form 
of  "cut-opens"  or  cans  intended  for  the  trade. 

The  slight  waste  incurred  by  cutting  open  cans  with  sound 
contents  is  insignificant  as  compared  with  the  incalculable  savings 
which  this  practice  may  make  possible  by  the  early  detection  of 
faulty  goods  and  the  prevention  of  their  recurrence,  by  enabling 
the  manufacturer  to  withdraw  suspicious  goods  from  the  market 
before  they  have  ruined  the  reputation  of  the  respective  brands,  and 
by  furnishing  a  reliable  check  on  the  work  of  the  employees,  whose 
knowledge,  that  their  product  is  subjected  to,  and  must  pass  a  rigid 
examination,  acts  as  a  moral  stimulus  for  high  quality,  skill  and 
carefulness. 

CHAPTER  XXXI. 

CHEMICAL  TESTS  AND  ANALYSES  OF  MILK,   SWEET- 
ENED CONDENSED  MILK,  EVAPORATED  MILK 
AND  MILK  POWDERS 

In  assembling  these  methods  of  analyses,  preference  has  been 
given  the  "Official  and  Provisional  Methods  of  Analysis,"  published 
by  the  American  Association  of  Official  Agricultural  Chemists.1 
The  official  methods  have  been  modified  and  supplemented  by  other 
methods  in  numerous  cases  wherever,  in  the  judgment  of  the  writer 
and  others,  such  modifications  and  substitutions  are  better  adapted 
for  analysis  of  these  special  products.  A  special  effort  has  further 
been  made  to  include  in  this  chapter  modifications  and  abbreviations 
of  tests  and  analyses,  adapted  for  the  use  of  the  factory  operator, 
whose  knowledge,  skill,  facilities  and  time  are  too  limited  to  enable 
him  to  successfully  follow  the  directions  of  the  official  methods,  or 
to  execute  delicate  and  difficult  chemical  analyses. 


1  United  States  Department  of  Agriculture,  Bureau  of  Chemistry,  Bulletin 
No.  107,  1912.  Also  Journal  of  the  Assn.  of  Official  Agr.  Chemists,  Vol.  II,  No.  3, 
Nov.  15,  1916. 


CPIEMICAI,  TESTS  AND  ANALYSES  261 

For  practical  factory  tests  of  fresh  milk  on  the  receiving  plat- 
form, determining  its  fitness  for  condensing,  the  reader  is  referred 
to  Chapter  III,  "Inspection  of  Milk  at  the  Condensery,"  pp.  44  to  49. 

Milk 

SPECIFIC  GRAVITY 

AEROMETRIC  METHOD  BY  MEANS  OF  THE  QUEVENNE  LACTOM- 
ETER. —  Use  an  accurate  Quevenne  lactometer  with  thermometer  at- 
tachment and  a  lactometer  cylinder  about  ten  inches  high  and  one 
and  one-half  inches  wide.  Fill  the  cylinder  with  milk  at  a  tem- 
perature between  5.5  and  65  degrees  F.  Insert  the  lactometer  and 
when  it  has  found  its  equilibrium,  note  the  point  on  the  scale  at  the 
surface  of  the  milk.  The  correct  temperature  is  60  degrees  F.  For 
every  degree  Fahrenheit  above  60  add  one-tenth  point  to  the  ob- 
served reading,  and  for  every  degree  Fahrenheit  below  60  deduct 
one-tenth  point  from  the  observed  reading.  This  rule  holds  good  only 
when  the  range  of  temperature  is  within  the  limits  of  55  degrees 
and  65  degrees  F. 

The  specific  gravity  is  calculated  by  adding  1,000  to  the  lactom- 
eter reading  and  dividing  the  sum  by  1,000.  Example:  Lactometer 
reading  is  31  at  65  degrees  F.  Corrected  reading  is  31.5; 

31.5  +  1000 
specific  gravity  is  - 


GRAVIMETRIC  DETERMINATION.  —  This  consists  of  the  filling  of 
a  perfectly  dry  picnometer  or  other  graduated  flask  of  known  meas- 
ure with  milk  at  the  standard  temperature  (60  degrees  F.,  or  15.5 
degrees  C.)  and  weighing  the  flask  and  contents.  The  weight  of 
the  flask  is  then  deducted  from  the  weight  of  the  flask  plus  con- 
tents and  the  difference  is  divided  by  the  weight  of  an  equal  volume 
of  water  at  standard  temperature.  The  result  is  the  specific  gravity 
of  the  milk. 

The  Westphal  balance  method  furnishes  another  accurate  means 
of  determining  the  specific  gravity.  Both  the  gravimetric  method 
and  the  Westphal  balance  method,  while  accurate  when  operated 
by  the  skillful  chemist,  require  considerable  time.  Experimental 
comparisons  have  demonstrated  that  for  all  practical  purposes  the 
Quevenne  hydrometer,  when  accurately  graduated,  yields  correct 
results,  and  the  simplicity  and  rapidity  of  its  operation  render  its 


262  CHEMICAL  TESTS  AND  ANALYSES 

use  in  the  determination  of  the  specific  gravity  of  milk  highly  ad- 
vantageous and  satisfactory. 

TOTAL   SOLIDS 

BY  MEANS  OF  THE  BABCOCK  FORMULA. — For  rapid  and  reason- 
ably accurate  work  the  total  solids  of  milk  may  be  determined  by 
the  use  of  the  Babcock  formula,  which  is  as  follows : 

Total  solids  =  -^ f-  1.2  X  f. 

L  =  Quevenne    lactometer   reading, 
f  =  per  cent  of  fat. 

Example :    Lactometer  reading  is  32 ;  per  cent  fat  is  4. 
Total  solids  =  ?j-  +  1.2  X  4  =  12.8  per  cent. 

GRAVIMETRIC  METHOD. — "Heat  from  three  to  five  grams  of 
milk  at  the  temperature  of  boiling  water  until  it  ceases  to  lose 
weight,  using  a  tared  flat  dish  of  not  less  than  5  c.c.  diameter.  If 
desired,  from  fifteen  to  twenty  grams  of  pure,  dry  sand  may  be 
previously  placed  in  the  dish.  Cool  in  a  desiccator  and  weigh  rapid- 
ly to  avoid  absorption  of  hygroscopic  moisture." 

ASH 

"Weigh  about  twenty  grams  of  milk  in  a  weighed  dish,  add 
6  c.c.  of  nitric  acid,  evaporate  to  dryness  and  ignite  at  a  tempera- 
ture just  below  redness  until  the  ash  is  free  from  carbon." 

TOTAL  NITROGEN 

Place  about  five  grams  of  milk  in  a  Kjeldahl  digestion  flask  and 
proceed,  without  evaporation,  as  described  under  "Gunning  Method" 
for  the  determination  of  nitrogen.  Multiply  the  percentage  of  nitro- 
gen by  6.38  to  obtain  nitrogen  compounds. 

GUNNING  METHOD 
APPARATUS 

(a)  Kjeldahl  flasks  for  both  digestion  and  distillation. — These 
are  flasks  having  a  total  capacity  of  about  550  c.c.,  made  of  hard, 
moderately  thick  and  well-annealed  glass.  When  used  for  distilla- 
tion the-  flasks  are  fitted  with  rubber  stopper^  and  bulb  tubes,  as 
given  under  distillation  flasks. 


CHSMICAI,  TESTS  AND  ANALYSES  263 

(b)  Kjeldahl  digestion  flasks. — These  are  pear-shape,  round- 
bottomed  flasks,  made  of  hard,  moderately  thick,  well-annealed  glass, 
having  a  total  capacity  of  about  250  c.c.    They  are  22  c.m.  long  and 
have  a  maximum  diameter  of  6  c.m.,  tapering  gradually  to  a  long 
neck,  which  is  2  c.m.  in  diameter  at  the  narrowest  part  and  flared  a 
little  at  the  edge. 

(c)  Distillation  flasks. — For  distillation  a  flask  of  ordinary 
shape,  of  about  550  c.c.  capacity  may  be  used.     It  is  fitted  with  a 
rubber  stopper  and  with  a  bulb  tube  above  to  prevent  the  possibility 
of  sodium  hydrate  being  carried  over  mechanically  during  distilla- 
tion.   The  bulbs  may  be  about  3  c.m.  in  diameter,  the  tubes  being  of 
the  same  diameter  as  the  condenser  and  cut  off  obliquely  at  the 
lower  end,  which  is  fastened  to  the  condenser  by  a  rubber  tube." 

PREPARATION  OF  REAGENTS 

"(a)     Potassium  sulphate. — This  reagent  should  be  pulverized 
before  using. 

(b)  Sulphuric  acid- — The  sulphuric  acid  should  have  a  specific 
gravity  of  1.84.     It  should  be  C.  P.  containing  no  nitrates  nor  am- 
monium sulphate. 

(c)  Sulphuric  acid. — AT-10  solution. 

(d)  Standard  alkali  solution. — The  strength  of  this  solution 
relative  to  the  acid  must  be  accurately  determined,  N-10  solution. 

(e)  Metallic  mercury  or  mercuric  oxid. — If  mercuric  oxid  is 
used  it  should  be  prepared  in  the  wet  way,  but  not  from  mercuric 
nitrate. 

(/)  Granulated  zinc  or  pumice  stone.. — One  of  these  reagents 
is  added  to  the  contents  of  the  distillation  flasks,  when  found  nec- 
essary, in  order  to  prevent  bumping. 

(g)  Potassium  sulphid  solution. — A  solution  of  forty  grams 
of  commercial  potassium  sulphid  in  one  liter  of  water. 

(h)  Sodium  hydroxid  solution. — A  saturated  solution  of  so- 
dium hydroxid  free  from  nitrates. 

(i)  Indicator. — A  solution  of  cochineal  is  prepared  by  digest- 
ing and  frequently  agitating  three  grams  of  pulverized  cochineal  in 
a  mixture  of  50  c.c.  of  strong  alcohol  and  200  c.c.  of  distilled  water 


264  CHEMICAL  TESTS  AND  ANALYSES 

for  a  day  or  two  at  ordinary  temperatures.    The  filtered  solution  is 
employed  as  indicator. 

DETERMINATION 

Place  the  substance  to  be  analyzed  in  a  digestion  flask,  employ- 
ing from  0.7  to  3.5  grams,  according  to  its  proportion  of  nitrogen. 
Add  10  grams  of  powdered  potassium  sulphate  and  from  15  to  25 
c.c.  (ordinarily  about  20  c.c.)  of  sulphuric  acid.  Conduct  the  diges- 
tion by  starting  with  a  temperature  below  boiling  point  and  increas- 
ing the  heat  gradually  until  frothing  ceases.  Digest  for  a  time 
after  the  mixture  is  colorless,  or  nearly  so,  or  until  oxidation  is  com- 
plete. Do  not  add  either  potassium  permanganate  or  potassium 
sulphid.  Dilute,  neutralize,  distil  and  titrate  with  standard  alkali. 
In  neutralizing,  it  is  convenient  to  add  a  few  drops  of  phenolphtha- 
lein  indicator,  by  which  one  can  tell,  when  the  acid  is  completely 
neutralized,  remembering  that  the  pink  color,  which  indicates  an 
alkaline  reaction,  is  destroyed  by  a  considerable  excess  of  strong 
fixed  alkali. 

CASEIN  AND  ALBUMIN 

"(a)  CASEIN. — The  determination  should  be  made  when  the 
milk  is  fresh,  or  nearly  so.  When  it  is  not  practicable  to  make  this 
determination  within  twenty-four  hours,  add  one  part  of  formal- 
dehyde to  twenty-five  hundred  parts  of  milk  and  keep  in  a  cool 
place.  Place  about  10  grams  of  milk  in  a  beaker  with  about  90  c.c. 
of  water  at  40  degrees  to  42  degrees  C.,  and  add  at  once  1.5  c.c.  of 
a  10  per  cent  acetic  acid  solution.  Stir  with  a  glass  rod  and  let 
stand  from  three  to  five  minutes  longer.  Then  decant  or  filter,  wash 
two  or  three  times  with  cold  water  by  decantation  and  transfer  pre- 
cipitate completely  to  filter.  Wash  once  or  twice  on  filter.  The 
filtrate  should  be  clear,  or  nearly  so.  If  it  be  not  clear  when  it  first 
runs  through,  it  can  generally  be  made  so  by  two  or  three  repeated 
filtrations,  after  which  the  washing  of  the  precipitate  can  be  com- 
pleted. Determine  nitrogen  in  the  washed  precipitate  and  filter  by 
the  Gunning  method.  To  calculate  the  equivalent  amount  of  casein 
from  the  nitrogen  multiply  by  6.38. 

In  working  with  milk  which  has  been  kept  with  preservatives, 
the  acetic  acid  should  be  added  in  small  proportions,  a  few  drops 
at  a  time,  with  stirring,  and  the  addition  continued  until  the  liquid 
above  the  precipitate  becomes  clear  or  very  nearly  so. 


CHKMICAI,  TSSTS  AND  ANALYSES  265 

(b)  AivBUMiN. — Exactly  neutralize  with  caustic  alkali  the  fil- 
trate obtained  in  the  preceding  operation  (a),  add  0.3  c.c.  of  a  10 
per  cent  solution  of  acetic  acid  and  heat  the  liquid  to  the  tempera- 
ture of  boiling  water  until  the  albumin  is  completely  precipitated, 
collect  the  precipitate  on  a  filter,  wash  and  determine  the  nitrogen 
therein.  Nitrogen  multiplied  by  6.38  equals  albumin,"  or 

To  the  filtrate  of  the  casein  determination  add  0.3  c.c.  of  10  per 
cent  acetic  acid,  boil  until  the  albumin  is  completely  precipitated  and 
proceed  as  directed  in  previous  paragraph. 

In  the  place  of  the  above  methods  the  per  cent  of  albumin  may 
be  determined  by  subtracting  the  per  cent  of  casein  from  the  per 
cent  of  total  nitrogen. 

MILK  SUGAR   (LACTOSE) 

OPTICAL  METHOD 
PREPARATION  OF  REAGENTS 

"(a)  Acid  mercuric  nitrate. — Dissolve  mercury  in  double  its 
weight  of  nitric  acid,  specific  gravity  1.42,  and  dilute  with  an  equal 
volume  of  water.  One  cubic  centimeter  of  this  reagent  is  sufficient 
for  the  quantities  of  milk  mentioned  below.  Larger  quantities  may 
be  used  without  affecting  the  results  of  polarization. 

(b)  Mercuric  iodid  with  acetic  acid. — Mix  33.2  grams  of  po- 
tassium iodid,  13.5  grams  of  mercuric  chlorid,  20  c.c.  of  glacial 
acetic  acid  and  640  c.c.  of  water." 

Determine  the  specific  gravity  of  the  milk  by  means  of  a  delicate 
hydrometer,  or,  if  preferred,  a  pycnometer.  The  quantity  of  sam- 
ple to  be  taken  for  the  determination  varies  with  the  specific  gravity 
and  is  to  be  measured  at  the  same  temperature  at  which  the  specific 
gravity  is  taken.  The  volume  to  be  measured  is  indicated  in  the  fol- 
lowing table,  which  is  based  upon  twice  the  normal  weight  of  lactose 
(32.9  grams  per  100  metric  c.c.)  for  the  Ventzke  sugar  scale. 

Place  the  quantity  of  milk  indicated  in  the  table  in  a  flask 
graduated  at  102.6  c.c.,  add  1  c.c.  of  the  acid  mercuric  nitrate  solu- 
tion or  30  c.c.  of  the  mercuric  iodid  solution  (an  excess  of  these  rea- 
gents does  no  harm),  fill  to  the  mark,  shake,  filter  through  a  dry 
filter  and  polarize.  It  is  not  necessary  to  heat  before  polarizing.  If 
a  200  m.m.  tube  is  used,  divide  the  polariscope  reading  by  2  (or,  if  a 
400  m.m.  tube  is  used,  by  4)  to  obtain  the  per  cent  of  lactose  in  the 
sample. 


266 


CHEMICAL  TESTS  AND  ANALYSES 


VOLUME  OF  MILK  CORRESPONDING  TO  A  LACTOSE  DOUBLE  NORMAL 

WEIGHT 


Specific    Gravity 
of  Milk. 

Volume    of   Milk 
for  a  Lactose 
Double  Normal 
Weight    Ventzke 
Scale. 

Specific    Gravity 
of  Milk. 

Volume    of   Milk 
for  a  Lactose 
Double  Normal 
Weight    Ventzke 
Scale. 

1.024 

C.  C. 

64.25 

1.031 

C.  C. 

63.80 

1.025 

64.20 

1.032 

63.75 

1.026 

64.15 

1.033 

63.70 

1.027 

64.05 

1.034 

63.65 

1.028 

64.00 

1.029 

63.95 

1.035 

63.55 

1.030 

63.90 

1.036 

63.50 

Low's  VOLUMETRIC  METHOD  MODIFIED 

PREPARATION  OF  REAGENTS 

"(a)     Copper  sulphate   solution. — Dissolve   34.639   grams   of. 
CuSO4  .5H2O  in  water  and  dilute  to  500  c.c. 

(b)  Alkaline  tartrate  solution. — Dissolve  173  grams  of  Ro- 
chelle  salts  and  50  grams  of  sodium  hydroxid  in  water  and  dilute 
to  500  c.c. 

(c)  Mixed  solution. — Mix  equal  volumes  of  solutions  (a)  and 
(b)  immediately  before  use. 

(d)  Standardisation  of  the  thiosulphate  solution. — Prepare  a 
solution  of  sodium  thiosulphate,  dissolving  24.659  grams  of  pure 
crystals  to  1,000  c.c.     Weigh  6.36  grams  copper  foil.     Dissolve  by 
warming  in  minimum  amount  of  nitric  acid  and  water  required. 
Boil  to  expel  the  red  fumes,  add  160  c.c.  strong  bromine  water  and 
boil  until  the  bromine  is  thoroughly  expelled.     Remove  from  the 
heat  and  add  a  slight  excess  of  strong  ammonium  hydroxid ;  223  c.c. 
is  about  the  right  amount.     Again  boil  until  the  excess  of  ammonia 
is  expelled,  as  shown  by  a  change  of  color  of  the  liquid,  and  partial 
precipitation.     Now  add  a  slight  excess  of  strong  acetic  acid  (100 
to  130  c.c.  of  80  per  cent  acid)   and  boil  for  a  minute.     Cool  to 
room  temperature  and  dilute  to  1,000  c.c.    Titrate  a  known  amount 
(10  to  15  c.c.)  of  the  copper  solution,  to  which  10  c.c.  of  a  25  per 
cent  solution  of  pure  potassium  iodid  has  been  added,  with  the 
thiosulphate  solution  until  the  brown  tinge  has  become  weak,  then 
add  sufficient  starch  liquor  to  produce  a  marked  blue  coloration. 


CHEMICAL  TESTS  AND  ANALYSES  267 

Continue  the  titration  cautiously  until  the  color  due  to  free  iodin 
has  entirely  vanished.  The  blue  color  changes  toward  the  end  to 
a  faint  lilac.  If  at  this  point  the  thiosulphate  be  added  drop  by  drop 
and  a  little  time  be  allowed  for  complete  reaction  after  each  addition, 
there  is  no  difficulty  in  determining  the  end  point  within  a  single 
drop.  One  cubic  centimeter  of  the  triosulphate  solution  will  be 
found  to  correspond  to  .00636  grams  of  copper." 

DETERMINATION  OF  COPPER 

"After  washing  the  precipitated  cuprous  oxid,  cover  the  gooch 
with  a  watch  glass  and  dissolve  the  oxid  by  means  of  5  c.c.  of  warm 
nitric  acid  (1 :1)  poured  under  the  watch  glass  with  a  pipette.  Catch 
the  filtrate  in  a  flask  of  250  c.c.  capacity,  wash  watch  glass  and 
gooch  free  of  copper;  50  c.c.  of  water  will  be  sufficient.  Boil  to 
expel  red  fumes,  add  5  c.c.  of  bromin  water,  boil  off  the  bromin  and 
proceed  exactly  as  in  standardizing  the  thiosulphate." 

DETERMINATION  OP  LACTOSE 

Place  50  c.c.  of  the  mixed  copper  reagent  in  a  beaker  and  heat 
to  the  boiling  point.  While  boiling  briskly  add  100  c.c.  of  the  lactose 
solution  containing  not  more  than  0.300  grams  of  lactose  and  boil 
for  six  minutes.  Filter  immediately  through  asbestos  and  wash. 
Obtain  the  weight  of  lactose  equivalent  to  the  weight  of  copper 
found  from  the  following  table : 


268 


CHEMICAL  TESTS  AND  ANALYSES 
FOR  THE  DETERMINATION  OF  LACTOSE  (SoxHLET-WEm)" 


Milli- 
grams 
of 
copper 

Milli- 
grams 
of 
lactose 

Milli- 
grams 
of 
copper 

Milli- 
grams 
of 
MefoM 

Milli- 
grams 
of 
copper 

Milli- 
grams 
of 
lactose 

Milli- 
grams 
of 
copper 

Milli- 
grams 
of 
lactose 

Milli- 
grams 
of 
copper 

Milli- 
grams 
of 
lactose 

100 

71.6 

160 

116.4 

220 

161.9 

280 

208.3 

340 

255.7 

101 

72.4 

161 

117.1 

221 

162.7 

281 

209.1 

341 

256.6 

102 

73.1 

162 

117.9 

222 

163.4 

282 

209.9 

342 

257.4 

103 

73.8 

163 

118.6 

223 

164.2 

283 

210.7 

343 

258.2 

104 

74.6 

164 

119.4 

224 

164.9 

284 

211.5 

344 

259.0 

105 

75.3 

165 

120.2 

225 

165.7 

285 

212.3 

345 

259.8 

106 

76.1 

166 

120.9 

226 

166.4 

286 

213.1 

346 

260.6 

107 

76.8 

167 

121.7 

227 

167.2 

287 

213.9 

347 

281.4 

108 

77.6 

168 

122.4 

228 

167.9 

288 

214.7 

348 

262.3 

109 

78.3 

169 

123.2 

229 

168.6 

289 

215.5 

349 

263.1 

110 

79.0 

170 

123.9 

230 

169.4 

290 

216.3 

350 

233.9 

111 

79.8 

171 

124.7 

231 

170.1 

291 

217.1 

264.7 

112 

80.5 

172 

125.5 

232 

170.9 

292 

217.9 

352 

265.5 

113 

81.3 

173 

126.2 

233 

171.6 

293 

218.7 

353 

263.3 

114 

82.0 

174 

127.0 

234 

172.4 

294 

219.5 

354 

267.2 

115 

82.7 

175 

127.8 

235 

173.1 

295 

220.3 

355 

268.0 

116 

83.5 

176 

128.5 

236 

173.9 

296 

221.1 

356 

268.8 

117 

84.2 

177 

129.3 

237 

174.6 

297 

221.9 

357 

289.6 

118 

85.0 

178 

130.1 

238 

175.4 

298 

222.7 

358 

270.4 

119 

85.7 

179 

130.8 

239 

176.2 

299 

223.5 

359 

271.2 

120 

86.4 

180 

131.6 

240 

176.9 

300 

224.4 

3-30 

272.1 

121 

87.2 

181 

132.4 

241 

177.7 

301 

225.2 

361 

272.9 

122 

87.9 

182 

133.1 

242 

178.5 

302 

225.9 

362 

273.7 

123 

88.7 

183 

133.9 

243 

179.3 

303 

226.7 

363 

274.5 

124 

89.4 

184 

134.7 

244 

180.1 

304 

227.5 

364 

275.3 

125 

90.1 

185 

135.4 

245 

180.8 

305 

228.3 

365 

276.2 

126 

90.9 

186 

136.2 

246 

181.6 

306 

229.1 

366 

277.1 

127 

91.6 

187 

137.0 

247 

182.4    , 

307 

229.8 

367 

277.9 

128 

92.4 

188 

137.7 

248 

183.2 

308 

230.6 

368 

278.8 

129 

93.1 

189 

138.5 

249 

184.0 

309 

231.4 

369 

279.6 

130 

93.8 

190 

139.3 

250 

184.8 

310 

232.2 

370 

283.5 

131 

94.6 

191 

140.0 

251 

185.5 

311 

232.9 

371 

281.4 

132 

95.3 

192 

140.8 

252 

186.3 

312 

233.7 

372 

282.2 

133 

96.1 

193 

141.6 

253 

187.1 

313 

234.5 

373 

283.1 

134 

96.9 

194 

142.3 

254 

187.9 

314 

235.3 

374 

283.9 

135 

97.6 

195 

143.1 

255 

183.7 

315 

236.1 

375 

284.8 

136 

98.3 

196 

143.9 

256 

189.4 

316 

236.8 

376 

285.7 

137 

99.1 

197 

144.6 

257 

190.2 

317 

237.6 

377 

286.5 

138 

99.8 

198 

145.4 

258 

191.0 

318 

238.4 

378 

287.4 

139 

100.5 

199 

146.2 

259 

191.8 

319 

239.2 

379 

288.2 

140 

101.3 

200 

146.9 

260 

192.5 

320 

240.0 

380 

289.1 

141 

102.0 

201 

147.7 

261 

193.3 

321 

243.7 

281 

289.9 

142 

102.8 

202 

148.5 

262 

194.1 

322 

241.5 

382 

290.8 

143 

103.5 

203 

149.2 

263 

194.9 

323 

242.3 

383 

291.7 

144 

104.3 

204 

150.0 

264 

195.7 

324 

243.1 

384 

292.5 

145 

105.1 

205 

150.7 

265 

196.4 

325 

243.9 

385 

293.4 

146 

105.8 

206 

151.5 

266 

197.2 

326 

244.6 

386 

294.2 

147 

106.6 

207 

152.2 

267 

198.0 

327 

245.4 

387 

295.1 

148 

107.3 

208 

153.0 

268 

198.8 

328 

246.2 

388 

236.0 

149 

108.1 

209 

153.7 

269 

199.5 

329 

247.0 

889 

296.8 

150 

108.8 

210 

154.5 

270 

200.3 

330 

247,7 

390 

297.7 

151 

109.6 

211 

155.2 

271 

201.1 

331 

248.5 

391 

298.5 

152 

110.3 

212 

156.0 

272 

201.9 

332 

249.2 

392 

299.4 

153 

111.1 

213 

156.7 

273 

202.7 

333 

250.0 

393 

300.3 

154 

111.9 

214 

157.5 

274 

203.5 

334 

250.8 

394 

331.1 

155 

112.6 

215 

158.2 

275 

204.3 

335 

251.6 

395 

302.0 

156 

113.4 

216 

159.0 

276 

205.1 

336 

252.5 

396 

302.8 

157 

114.1 

217 

159.7 

277 

205.9 

337 

253.3 

397 

308.7 

158 

114.9 

218 

160.4 

278 

206.7 

338 

254.1 

398 

304.6 

159 

115.6 

219 

161.2 

279 

207.5 

339 

254.9 

399 

305.4 

400 

306.3 

CHEMICAL  TESTS  AND  ANALYSES  269 

BUTTER  FAT 

THE  BABCOCK  TEST 

STANDARD  GLASSWARE.1 

(a)  Standard  milk  test  bottles,  graduated  to  8  per  cent  and 
with  sub-divisions  of  .1  per  cent. 

(b)  Pipette  graduated  to  17.6  c.c. 

(c)  Acid  measure  graduated  to  17.5  c.c. 

(d)  Centrifuge-Babcock  tester. 

(e)  Water  bath  for  reading  at  135  to  140  degrees  F. 

(f)  Calipers  for  measuring  fat  column. 

(g)  Sulphuric  acid,  specific  gravity  1.82  to  1.83. 

DETERMINATION 

Pipette  17.6  c.c.  of  the  properly  mixed  sample  of  milk  into  the 
milk  test  bottle.    Add  17.5  c.c.  of  acid  and  shake  until  all  the  curd 


Fig.    65.     Babcock    tester 

Courtesy  of  Creamery  Package  Mfg. 

Company 

is  completely  dissolved.  Both  milk  and  acid  should  have  a  temper- 
ature of  55  to  70  degrees  F.  If  milk  and  acid  are  too  warm,  set 
the  sample  bottles  and  the  acid  jar  into  a  trough  or  tub  of  water  at 
55  to  70  degrees  F.  for  thirty  minutes  before  testing.  The  test 

1  Hunziker,   Indiana  Agricultural   Experiment   Station,   Circulars   41   and  42. 
1914. 


270  CHEMICAL  TESTS  AND  ANALYSES 

bottles  containing  the  mixture  of  milk  and  acid  are  then  whirled  in 
the  Babcock  tester  for  five  minutes  at  about  one  thousand  revolu- 
tions per  minute,  in  the  case  of  a  tester  with  a  twelve-inch  diameter 
wheel.  Fill  the  test  bottles  to  the  bottom  of  the  neck  with  hot 
water.  The  water  should  be  soft,  preferably  rain  water  or  distilled 
water.  If  hard  tap  water  is  used  it  should  be  boiled  to  precipitate 
the  carbonates,  otherwise  the  test  may  be  difficult  to  read,  owing  to 
the  presence  of  bubbles  of  gas  on  top  of  the  fat  column.  Revolve 
again  at  full  speed  for  two  minutes,  fill  the  test  bottles  to  near  the 
top  of  the  graduation  with  hot  water.  Whirl  in  the  centrifuge  for 
one  minute.  Now  set  the  test  bottles  in  the  Water  bath  at  135 
degrees  F.  for  five  minutes.  The  test  is  now  ready  to  be  read. 
The  figures  on  the  test  bottles  represent  per  cent.  In  the  case  of 
the  8  per  cent  standard  milk  test  bottle  the  sub-divisions  represent 
tenths  per  cent.  Read  from  the  bottom  of"  the  lower  curve  to  the 
top  of  upper  curve  of  the  fat  column,  including  the  meniscus  in  the 
reading. 

GRAVIMETRIC  METHOD— PAPER  COIL 

"Make  coils  of  thick  filter  paper,  cut  into  strips  6.25  by  62.5 
c.m.,  and  thoroughly  extract  with  ether  and  alcohol,  or  correct  the 
weight  of  the  extract  by  a  constant  obtained  for  the  paper.  From 
a  weighing  bottle  or  weighing  pipette,  transfer  about  5  grams  of 
milk  to  the  coil,  care  being  taken  to  keep  the  end  of  the  coil  held 
.in  the  fingers,  dry.  Dry  the  coil,  dry  end  down,  on  a  piece  of  glass 
at  the  temperature  of  boiling  water;  transfer  to  an  extraction  ap- 
paratus and  extract  with  absolute  ether  or  petroleum  ether  boiling 
at  about  45  degrees  C. ;  dry  the  extracted  fat  and  weigh." 

ROESE-GOTTLIEB  METHOD 

"Weigh  10-11  grams  of  the  milk  into  a  Rohrig  tube  or  some  sim- 
ilar apparatus,  add  1.25  c.c.  of  concentrated  ammonium  hydroxid 
(2  c.c.  if  the  sample  is  sour)  and  mix  thoroughly.  Add  10  c.c.  of 
95  per  cent  alcohol  by  volume  and  mix  well.  Then  add  25  c.c.  of 
washed  ether  and  shake  vigorously  for  thirty  seconds,  then  25  c.c. 
of  petroleum  ether  (redistilled  slowly  at  a  temperature  below  60  de- 
grees C.)  and  shake  again  for  thirty  seconds.  Let  stand  twenty 
minutes,  or  until  the  upper  liquid  is  practically  clear.  Draw  off  as 
much  as  possible  of  the  ether-fat  solution  (usually  0.5-0.8  c.c.  will 


CHEMICAL  TESTS  AND  ANALYSES  271 

be  left)  into  a  weighed  flask  through  a  small  quick-acting  filter.  The 
flask  should  always  be  weighed  with  a  similar  one  as  a  counterpoise. 
Re-extract  the  liquid  remaining  in  the  tube,  this  time  with  only  15 
c.c.  of  each  ether,  shake  vigorously  thirty  seconds  with  each  and  al- 
low to  settle.  Draw  off  the  clear  solution  through  the  small  filter 
into  the  same  flask  as  before  and  wash  the  tip  of  spigot,  the  funnel 
and  the  filter  with  a  few  c.c.  of  a  mixture  of  the  two  ethers  in  equal 
parts.  For  absolutely  exact  results  the  re-extraction  must  be  re- 
peated. This  third  extraction  yields  usually  not  more  than  about  1 
mg.  of  fat  (about  0.02  per  cent  on  a  4  gram  charge)  if  the  previous 
ether-fat  solutions  have  been  drawn  off  closely.  Evaporate  the 
ethers  slowly  on  a  steam  bath,  then  dry  the  fat  in  a  boiling  water 
oven  to  constant  weight. 

Confirm  the  purity  of  the  fat  by  dissolving  in  a  little  petroleum 
ether.  Should  a  residue  remain,  remove  the  fat  completely  with 
petroleum  ether,  dry  the  residue,  weigh  and  deduct  the  weight. 
Finally  correct  this  weight  by  a  blank  determination  on  the  reagents 
used." 

Sweetened  Condensed  Milk 

PREPARATION  OF  SAMPLE 

Pour  the  contents  of  the  can  into  a  bowl  or  on  a  glass  plate. 
Scrape  out  the  can  thoroughly,  removing  all  the  sugar  sediment  from 
the  top  and  bottom  of  the  can.  Mix  thoroughly  with  pestle  or  spa- 
tula until  a  homogenous  emulsion  is  secured.  This  is  important, 
as  it  is  exceedingly  difficult  to  secure  a  representative  sample  other- 
wise. 

If  it  is  desired  to  use  a  40  per  cent  solution  as  directed  in  the 
determination  of  the  individual  ingredients,  weigh  accurately  40 
grams  of  the  properly  mixed  contents  of  the  can  into  a  100  c.c 
graduated  flask.  Add  60  c.c.  of  water.  The  sweetened  condensed 
milk  mixes  somewhat  difficultly  with  the  water.  Complete  solution 
is  facilitated  by  adding  the  water  in  several  installments,  shaking 
after  each  addition  until  condensed  milk  sediment  adheres  no  longer 
to  the  bottom  and  sides  of  the  flask. 


272  CHSMICAI,  TSSTS  AND  ANALYSES 

SPECIFIC  GRAVITY 

ASROMETRIC  METHOD  BY  M^ANS  OF  BEAUME  HYDROMETER 

*  APPARATUS 

Beaume  Hydrometer. — Use  a  specially  constructed  Beaume 
hydrometer  with  mercury  bulb,  and  a  scale  of  30  to  37  degrees  B., 
graduated  to  tenths  degrees.  Length  over  all,  twelve  inches ;  length 
of  spindel,  six  inches ;  length  of  empty  bulb,  four  and  one-quarter 
inches;  width  of  empty  bulb,  thirteen-sixteenths  of  one  inch. 

Hydrometer  Jar. — Use  a  glass  or  tin  cylinder  with  substantial 
base,  minimum  length  twelve  inches,  minimum  width  one  and  a  half 
inches. 

DETERMINATION 

The  Beaume  hydrometer  is  graduated  to  read  correctly  at  60 
degrees  F.  (15.5  degrees  C.).  At  this  temperature  the  sweetened 
condensed  milk  is  too  viscous  for  rapid  and  accurate  work.  Warm 
the  condensed  milk  to  100  degrees  F.  or  above  and  correct  the 
Beaume  reading  by  adding  to  the  observed  reading  -025  points  for 
every  degree  Fahrenheit  above  60.  At  a  temperature  of  100  degrees 
F.  or  above,  the  reading  can  be  made  in  fifteen  minutes  or  less,  after 
the  hydrometer  is  inserted  in  the  milk. 

The  specific  gravity  is  determined  by  the  use  of  the  following 
formula : 

c       .,  144.3 

Specific  gravity  :       144  3  _  R 

B  =  Beaume  reading  at  60  degrees  F. 
Fyxample:    Observed  Beaume  reading  at  120  is  31.6. 

Corrected  reading  =  31.6  +  [(120  —  60)   X  -025]  =  33.1 

|  Specific  gravity  =    ^j4^   -  1.2977         fgj       : 

The  following  table  shows  the  specific  gravity  of  sweetened 
condensed  milk  when  the  Beaume  reading  is  known. 


CHEMICAL  TESTS  AND  ANALYSES 


273 


BeaumS 

Specific 
gravity 

Beaume1 

Specific 
gravity 

Beaum6 

Specific 
gravity 

0 

1.000 

16.5 

1130 

29.7 

1:260 

0.7 

1.005 

17.1 

1.135 

30.2 

1.265 

1.4 

1.010 

1.77 

1.140 

30.6 

1.270 

2.1 

1.015 

18.3 

1.145 

31.1 

1.275 

2.7 

1.020 

18.8 

1.150 

31.5 

1.280 

3.4 

1.025 

19.3 

1.155 

32.0 

1.285 

4.1 

1.030 

19.8 

1.160 

32.4 

1.290 

4.7 

1.035 

20.3 

1.165 

32.8 

1.295 

5.4 

1.040 

20.9 

1.170 

33.3 

1.300 

6.0 

1.045 

21.4 

1.175 

33.7 

1.305 

6.7 

1.050 

22.0 

1.180 

34.2 

1.310 

7.4 

1.055 

22.5 

1.185 

34.6 

1.315 

8.0 

1.060 

23.0 

1,190 

35.0 

1.320 

8.7 

1.065 

23.5 

1,195 

35.4 

1.325 

9.4 

1.070 

24.0 

1,200 

35.8 

1.330 

10.0 

1.075 

24.5 

1.205 

36.2 

1.335 

10.6 

1.080 

25.0 

1.210 

36.6 

1.340 

11.2 

1.085 

25.5 

1.215 

37.0 

1.345 

11.9 

1.090 

26.0 

1.220 

37.4 

1.350 

12.4 

1.095 

26.4 

1.225 

37.8 

1.355 

13.0 

1.100 

26.9 

1.230 

38.2 

1.360 

13.6 

1.105 

27.4 

1.235 

38.6 

1.365 

14.2 

1.110 

27.9 

1.240 

39.0 

1.370 

14.9 

1.115 

28.4 

1.245 

39.4 

1.375 

15.4 

1.120 

28.8 

1.250 

39.8 

1.380 

16.0 

1.125 

29.3 

1.255 

40.1 

1.385 

GRAVIMETRIC  DETERMINATION 

Dilute  a  measured  portion  of  a  40  per  cent  solution  with  an 
equal  volume  of  water,  use  5  c.c.  of  the  diluted  mixture,  correspond- 
ing to  1  gram  of  the  condensed  milk  and  proceed  as  directed  under 
"Milk,"  page  262. 

TOTAL  SOLIDS 

Dilute  a  measured  portion  of  a  40  per  cent  solution  with  an 
equal  volume  of  water,  measure  5  c.c.  of  the  diluted  mixture,  cor- 
responding to  1  gram  of  the  condensed  milk  into  an  evaporating 
dish  containing  15  to  20  grams  of  pure  dry  sand  and  proceed  as 
directed  under  "Milk,"  page  262. 

ASH 

Ignite  the  total  solids  at  very  low  redness,  cool,  and  weigh- 
See  "Milk,"  page  262. 


274  CHEMICAL  TESTS  AND  ANALYSES 

PROTEIDS 

Determine  nitrogen  in  5  c.c.  of  the  40  per  cent  solution  accord- 
ing to  the  Gunning  method,  see  "Milk,"  page  262,  and  multiply  the 
results  by  6.38. 

LACTOSE 

Dilute  five  grams  of  a  40  per  cent  solution  to  about  40  c.c.  and 
add  .6  c.c.  of  Fehling's  copper  solution.  Nearly  neutralize  with 
sodium  hydroxide,  make  up  to  100  c.c.,  filter  through  dry  filter  and 
determine  lactose  in  an  aliquot  as  directed  under  "Milk — Determina- 
tion of  Lactose,"  page  266. 

FAT 
MODIFIED  BABCOCK  TEST 

Weigh  eighteen  grams,  or  measure  16.1  c.c.  of  the  40  per  cent 
solution  into  a  standard  Babcock  milk  test  bottle.  Add  4  c.c.  of 
commercial  sulphuric  acid,  specific  gravity  1.82  to  1.83.  Shake  im- 
mediately until  acid  is  thoroughly  mixed  with,  the  milk.  Whirl  in 
Babcock  tester  for  six  minutes  at  full  speed.  The  centrifuge  must 
run  smoothly.  Stop  the  tester  gradually  and  remove  the  bottles 
carefully  so  as  not  to  break  the  layer  of  floating  curd.  Decant  the 
clear  whey  by  slowly  inclining  the  bottle.  Now  add  two-thirds  of 
a  17.6  c.c.  pipette  full  of  water-  After  thoroughly  shaking  to 
emulsify  the  curd  and  to  wash  it  free  of  sucrose,  add  4  c.c.  sulphuric 
acid,  shake,  whirl  afid  decant  as  before.  Then  add  one  17.6  c.c. 
pipette  full  of  water,  17.5  c.c.  of  sulphuric  acid  and  complete  the 
Babcock  test  in  the  usual  way  as  directed  under  "Milk,"  page  269. 
Multiply  the  reading  by  2.5. 

This  method  yields  very  satisfactory  results  with  sweetened 
condensed  milk  containing  not  less  than  4  to  5  per  cent  fat.  With 
condensed  milk  of  a  lower  fat  content  the  decanting  of  the  clear 
whey  is  difficult,  since  the  curd  in  the  partly  skimmed  product  is 
too  heavy  to  float  in  the  form  of  a  firm  cheese. 

THE  ROESE  GOTTLIEB  METHOD 

As  practiced  in  the  Dairy  Laboratory,  Bureau  of  Chemistry, 
Department  of  Agriculture 

"Weigh  out  4  to  5  grams  of  the  homogeneous  sample  of  con- 
densed milk  into  a  Rohrig  tube  (Zeit.  Unters  Nahr.  u.  Genussm., 


CHEMICAL  TESTS  AND  ANALYSES  275 

1905,  9:531)  or  some  similar  apparatus  and  dilute  with  water  in 
the  tube  to  about  10.5  c.c. — or,  if  preferred,  weigh  into  the  tube  10 
to  11  grams  of  a  40  per  cent  solution  of  the  substance — add  1%  c.c. 
of  concentrated  ammonium  hydroxid  (2  c.c.  if  the  sample  be  sour) 
and  mix  thoroughly  with  the  milk.  Add  10  c.c.  of  95  per  cent 
alcohol  and  mix  well.  Then  add  25  c.c.  of  washed  ethyl  ether  and 
shake  vigorously  for  half  a  minute,  then  add  25  c.c.  of  petroleum 
ether  (redistilled  slowly  at  a  temperature  below  60  degrees  C.  pre- 
ferably) and  shake  again  for  half  a  minute.  Let  stand  20  minutes 
or  until  the  upper  liquid  is  practically  clear  and  its  own  lower  level 
constant.  Draw  off  of  the  ether  solution  as  much  as  possible — 
usually  0.5  to  0.8  c.c.  will  be  left — into  a  weighed  flask  through  a 
diminutive  quick  acting  filter,  of  selected  paper.  The  flask  should 
always  be  weighed  with  a  similar  one  as  counterpoise. 

"Re-extract  the  liquid  remaining  in  the  tube,  this  time  with 
only  15  c.c.  of  each  ether,  shaking  vigorously  half  a  minute  with 
each,  and  allow  to  settle. 

"Draw  off  the  clear  solution  through  the  small  filter  into  the 
same  flask  as  before  and  wash  the  tip  of  the  spigot,  the  funnel  and 
the  filter  with  a  few  c.c.  of  a  mixture  of  the  two  ethers  in  equal  parts 
(previously  mixed  and  free  from  deposited  water). 

"For  perfectly  exact  results  the  re-extraction  must  be  repeated. 
This  extraction  yields  usually  not  more  than  about  a  milligram  of 
fat,  if  the  previous  ether-fat-solutions  have  been  drawn  off  closely — 
an  amount  averaging  about  -02  per  cent  on  a  4-gram  charge. 

"Evaporate  the  ether  .slowly  on  a  steam  bath,  then  dry  the  fat 
in  a  boiling  water  oven  until  loss  of  weight  ceases. 

"Prove  the  purity  of  the  fat  by  dissolving  in  a  little  petroleum 
ether.  Should  a  residue  remain,  wash  the  fat  out  completely  with 
petroleum  ether,  dry  the  residue,  weigh,  and  deduct  the  weight. 
(This  should  not  often  be  necessary.) 

"Finally  deduct  the  weight  obtained  by  blank  determination  on 
the  chemicals  used. 

"By  this  method  practically  absolute  results  can  be  obtained." 

SUCROSE 

Determine  by  difference,  deducting  the  milk  solids  (ash  plus 
proteids  plus  lactose  plus  fat)  from  the  total  solids,  or  invert  the 
sucrose,  determine  the  total  invert  sugar,  deduct  from  this  the 


276  CHEMICAL  TESTS  AND  ANALYSES 

lactose  calculated  as  invert  sugar  and  calculate  the  difference  as 
sucrose. 

MILK  SOLIDS 

Deduct  the  per  cent  sucrose  from  the  per  cent  total  solids.  The 
difference  represents  the  per  cent  milk  solids. 

Evaporated  Milk 

PREPARATION  OF  SAMPLE 

Shake  the  can  of  evaporated  milk  vigorously  before  opening. 
If,  upon  opening  the  can,  separated  cream  or  small  lumps  of  butter 
are  found  to  adhere  to  the  seams  and  around  the  junction  of  the 
ends  and  the  body,  set  the  can  in  a  water  bath  at  130  degrees  F.  for 
ten  minutes  or  until  all  fat  is  completely  dissolved.  Then  pour  the 
entire  contents  into  a  beaker  and  pour  back  and  forth  several  times 
until  a  homogeneous  mixture  is  secured.  If  it  is  known  before 
opening  the  can  that  the  contents  are  separated,  submerge  the  whole 
can  in  a  water  bath  at  130  degrees  F.  for  ten  minutes,  then  shake, 
open  and  proceed  as  above. 

If  it  is  desired  to  use  a  40  per  cent  solution,  as  directed  under 
the  determination  of  the  individual  ingredients,  weigh  accurately 
40  grams  of  the  properly  mixed  contents  of  the  can  into  a  100  c.c. 
graduated  flask-  Add  60  c.c.  water  and  mix  thoroughly  by  shaking 
or  stirring. 

SPECIFIC  GRAVITY 

AEROMETRIC  METHOD 
APPARATUS 

Beaume  hydrometer. — Use  a  special  Beaume  hydrometer  with 
a  scale  ranging  from  five  to  twelve  points,  graduated  to  tenths  de- 
grees and  mercury-weighted.  Length  over  all  eleven  inches,  length 
of  spindle  six  inches,  length  of  empty  bulb  four  inches  and  width 
of  empty  bulb  seven-eighths  inch. 

Hydrometer  jar. — -Use  a  glass  or  tin  cylinder  with  substantial 
base.  Minimum  height  ten  inches  and  minimum  width  one  and  a 
half  inches. 

DETERMINATION 

The  Beaume  hydrometer  is  graduated  to  read  correctly  at  60 
degrees  F.  (15.5  degrees  C.).  For  every  degree  Fahrenheit  above 


CHEMICAI,  TESTS  AND  ANALYSES  277 

60  add  .0313  points  to  the  observed  reading.     For  every  degree 
Fahrenheit  below  60,  deduct  .0313  points  from  the  observed  reading. 
The  specific  gravity  is  determined  by  the  use  of  the  following 
formula  : 

145.5 
Specific  gravity  :       145  5  _  R 

B  =  Corrected  Beaume  reading 
Example  :    Beaume  reading  at  80  degrees  F.  is  7.8 

Corrected  reading  =  7-8  +  [(80  —  60)  X  .0313]  =  8.43 

145  5 
Specific  gravity  =  =   145-5Ja43 

Equally  good  results  may  be  obtained  by  diluting  the  evaporated 
milk  with  an  equal  weight  of  water.  Then  take  the  Quevenne  lac- 
tometer reading  at  60  degrees  F.  Multiply  the  reading  by  2,  add 
1000,  and  divide  by  1000. 

GRAVIMETRIC  DETERMINATION 

Dilute  the  evaporated  milk  with  four  times  its  weight  of  water 
and  proceed  as  directed  under  "Milk,"  page  262. 

TOTAL  SOLIDS 

BY  MEANS  OF  SPECIFIC  GRAVITY  AND  BABCOCK  FORMULA 
Determine  the  specific  gravity  as  above  directed.     Multiply  by 
1000  and  subtract  1000.     Then  use  the  following  formula: 


L  =  The  figure  derived  from  the  specific  gravity  by  above 
calculations 

f  =  per  cent  fat 

Example:  Evaporated  milk  tests  7.8  per  cent  fat  and  has  a 
specific  gravity  of  1.0615 

L  =  (1.0615  X  1000)  —  1000  =  61.5 

Total  solids  •=  --  +  1.2  X  7.8  =  24.74  per  cent. 


278 


CHEMICAL,  TESTS  AND  ANALYSES 


For  rapid  determination  of  the  total  solids  of  evaporated  milk 
the  factory  operator  is  referred  to  the  following  tables  from  which 
the  per  cent  total  solids  may  be  read  at  a  glance  when  the  Beaume 
reading  at  60  degrees  F.  and  the  per  cent  fat  are  known. 

Per  Cent  Solids  of  Evaporated  Milk 

The  Beaume  Degrees  at  60  Degrees  F.  are  Indicated  in  the  Horizon- 
tal Line  at  the  Top.     The  Per  Cent  of  Fat  is  Shown  in 
the  Vertical  Column  at  the  Left 


Beaume  reading  at  60  degrees  Fahrenheit 


FAT 
PER 
CENT 

8.0 

8.1 

8.2 

8.3 

8.4 

8.5 

8.6 

8.7 

8.8 

8.9 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 

ceat. 

6.0 

21.75 

21.94 

22.13 

22.32 

22.52 

22.71 

22.90 

23.10 

23.29 

23.49 

6.2 

21.99 

22.18 

22.37 

22.56 

22.76 

22.95 

23.14 

23.34 

23.53 

23.73 

6.4 

22.23 

22.42 

22.61 

22.80 

23.00 

23.19 

23.38 

2358 

23.77 

23.97 

6.6 

22.47 

22.66 

22.85 

23.04 

23.24 

23.43 

23.62 

23.82 

24.01 

24.21 

6.8 

22.71 

22.90 

23.09 

23.28 

23.48 

23.67 

23.86 

24.06 

24.25 

2445 

7.0 

22.95 

23.14 

23.33 

23.52 

23.72 

23.91 

24.10 

24.30 

24.49 

24.69 

7.2 

23.19 

23.38 

23.57 

23.76 

23.96 

24.15 

24.34 

24.54 

24.73 

24.93 

7.4 

23.43 

23.62 

23.81 

24.00 

24.20 

24.39 

24.58 

24.78 

24.97 

25.17 

7.6 

23.67 

23.86 

24.05 

24.24 

24.44 

24.63 

24.82 

25.02 

25.21 

25.41 

7.8 

23.91 

24.10 

24.29 

24.48 

24.68 

24.87 

25.06 

25.26 

25.45 

25.65 

8.0 

24.15 

24.34 

24.53 

2472 

24.92 

2511 

25.30 

25.50 

25.69 

25.89 

8.2 

24.39 

24.58 

24.77 

24.96 

25.16 

25.35 

25.54 

25.74 

25.93 

26.13 

8.4 

24.63 

24.82 

25.01 

25.20 

25.40 

25.59 

25.78 

25.98 

26.17 

26.37 

8.6 

24.87 

25.06 

25.35 

25.44 

25.64 

25.83 

26.02 

26.22 

26.41 

26.61 

8.8 

25.11 

25.30 

25.49 

25:68 

25.88 

26.07 

26.26 

26.46 

26.65 

26.85 

9.0 

25.35 

25.54 

25.73 

25.92 

2612 

26.31 

26.50 

26.70 

26.89 

27.09 

9.2 

25.59 

25.78 

25.97 

26.16 

26.36 

26.55 

26.74 

26.94 

27.13 

27.38 

9.4 

25.83 

26.02 

26.21 

26.40 

26.60 

26.79 

26.98 

27.18 

27.37 

27.57 

9.6 

26.07 

26.26 

26.45 

26.64 

26.84 

27.03 

27.22 

27.42 

27.61 

27.81 

9.8 

26.31 

26.50 

26.69 

26.88 

2708 

27.27 

2746 

27.66 

27.85 

28.05 

10.0 

26.55 

26.74 

26.93 

27.12 

27.32 

27.51 

27.70 

27.90 

28.09 

28.29 

10.2 

26.79 

26.98 

27.17 

27.36 

27.56 

27.75 

27.94 

28.14 

28.33 

28.53 

10.4 

27.03 

27.22 

27.41 

27.60 

27.80 

27.99 

28.18 

2838 

28.57 

28.77 

10.6 

27.27 

27.46 

27165 

27.84 

28.04 

28.23 

28.42 

28.62 

28.81 

29.01 

10.8 

2751 

2770 

27.89 

28.08 

28.28 

28.47 

28.66 

28.86 

29.05 

29.25 

11.0 

2775 

27.94 

28.13 

28.32 

28.52 

28.71 

28.90 

29.10 

29.29 

29.49 

11.2 

27.99 

28.18 

28.37 

28.56 

28.76 

28.95 

29.14 

29.34 

29.53 

29.73 

11.4 

28.23 

28.42 

28.61 

28.80 

29.00 

29.19 

29.38 

29.58 

29.77 

29.97 

11.6 

28.47 

28.66 

28.85 

29.04 

29.24 

29.43 

29.62 

29.82 

30.01 

30.21 

11.8 

28.71 

28.90 

29.09 

29.28 

29.48 

29.67 

29.86 

30.06 

30.25 

30.45 

CHEMICAL  TESTS  AND  ANALYSES 


279 


Per  Cent  Solids  of  Evaporated  Milk   (Continued) 

The  Beaume  Degrees  at  60  Degrees  F.  are  Indicated  in  the  Horizon- 
tal Line  at  the  Top.     The  Per  Cent  of  Fat  is  Shown 
in  the  Vertical  Column  at  the  Left 


Beaume  reading  at  60  degrees  Fahrenheit 


FAT 
PER 
CENT 

9.0 

9.1 

9.2 

9.3 

9.4 

9.5 

9.6 

9.7 

9.8 

9.9 

Solids 
per 
cent 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent 

6.0 

23.68 

23.88 

24.08 

24.27 

24.47 

24.66 

24.86 

25.06 

25.26 

25.45 

6.2 

23.92 

24.12 

24.32 

24.51 

24.71 

24.90 

25.10 

25.30 

25.50 

25.69 

6.4 

24.16 

24.36 

24.56 

24.75 

24.95 

25.14 

25.34 

25.51 

25.74 

25.93 

6.6 

24.40 

24.60 

24.80 

24.99 

25.19 

25.38 

25.58 

25.78 

25.98 

26.17 

6.8 

24.64 

24.84 

25.04 

25.23 

25.43 

25.62 

25.82 

26.02 

26.22 

26.41 

7.0 

24.88 

25.08 

25.28 

25.47 

25.67 

25.86 

26.06 

26.26 

26.46 

26.65 

7.2 

25.12 

25.32 

25.52 

25.71 

25.91 

26.10 

26.30 

26.50 

26.70 

26.89 

7.4 

25.36 

25.56 

25.76 

25.95 

26.15 

26.34 

26.54 

26.74 

26.94 

27.13 

7.6 

25.60 

25.80 

26.00 

26.19 

26.39 

26.58 

26.78 

26.98 

27.18 

27.37 

7.8 

25.84 

26.04 

26.24 

26.43 

26.63 

26.82 

27.02 

2722 

27.42 

27.61 

8.0 

26.08 

26.28 

26.48 

26.67 

26.87 

27.06 

27.26 

27.46 

27.66 

27.85 

8.2 

26.32 

26.52 

26.72 

26.91 

27.11 

27.30 

27.50 

27.70 

27.90 

28.09 

8.4 

26.56 

26.76 

26.96 

27.15 

27.35 

27.54 

27.74 

27.94 

28.14 

28.33 

8.6 

26.80 

27.00 

27.20 

27.39 

27.59 

27.78 

27.98 

2818 

28.38 

28.57 

8.8 

27.04 

27.24 

27.44 

2763 

27.83 

28.02 

28.22 

2842 

28.62 

28.81 

9.0 

27.28 

27.48 

27.68 

27.87 

28,07 

28.26 

28.46 

28.66 

28.86 

29.05 

9.2 

27.52 

27.72 

27.92 

28.11 

28.31 

28.50 

28.70 

28.90 

29.10 

29.29 

9.4 

27.76 

27.96 

28.16 

28.35 

28.55 

28.74 

28.94 

29.14 

29.34 

29.53 

9.6 

28.00 

28.20 

28.40 

28.59 

28.79 

28.98 

29.18 

29.38 

29.5S 

29.77 

9.8 

28.24 

28.44 

28.64 

28.83 

29.03 

29.22 

29.42 

29.62 

29.82 

sa.oi 

10.0 

28.48 

28.68 

28.88 

29.07 

29.27 

29.46 

29.66 

29.86 

30.06 

30.25 

10.2 

28.72 

28.92 

29.12 

29.31 

29.51 

29.70 

29.90 

30.10 

30.30 

30.49 

10.4 

28.96 

29.16 

29.36 

29.55 

29.75 

29.94 

30.14 

30.34 

30.54 

30.73 

10.6 

29.20 

29.40 

29.60 

29.79 

29.99 

30.18 

30.33 

3058 

30.78 

30.97 

10.8 

29.44 

29.64 

29.84 

30.03 

30.23 

30.42 

30.62 

30.82 

31.02 

31.21 

i 

11.0 

29.68 

29.88 

30.08 

30.27 

30.47 

30.66 

30.86 

31.06 

31.26 

31.45 

11.2 

29.92 

30.12 

30.32 

30.51 

30.71 

30.90 

31.10 

31.30 

31.50 

3L69 

11.4 

30.16 

30.36 

30.56 

30.75 

30.95 

31.14 

3134 

31.54 

31J4 

31.93 

11.6 

30.40 

30.60 

30.80 

30.99 

31.19 

31.38 

3158 

31.78 

31.98 

32.17 

11.8 

30.64 

30.84 

31.04 

31.23 

31.43 

31.62 

31.82 

32.02 

3222 

3241 

280 


CHSMICAI,  TESTS  AND  ANALYSES 


Per  Cent  Solids  of  Evaporated  Milk   (Continued) 

The  Beaume  Degrees  at  60  Degrees  F.  are  Indicated  in  the  Horizon- 
tal line  at  the  Top.     The  Per  Cent  of  Fat  is   Shown 
in  the  Vertical  Column  at  the  Left 


Beaume  reading  at  60  degrees  Fahrenheit 


FAT 
PER 

CENT 

10.0 

10.1 

10.2 

10.3 

10.4 

10.5 

10.6 

10.7 

10.8 

10.9 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

Solids 
per 
cent. 

6.0 

25.65 

25.85 

26.05 

26.25 

26.45 

26.65 

26.85 

27.05 

27.25 

27.45 

6.2 

25.89 

26.09 

26.29 

26.49 

26.69 

26.89 

27.09 

27.29 

27.49 

27.69 

6.4 

26.13 

26.33 

26.53 

26.73 

26.93 

27.13 

27.33 

27.53 

27.73 

27.93 

6.6 

26.37 

26.57 

26.77 

26.97 

27.17 

27.37 

27.57 

27.77 

27.97 

28.17 

6.8 

26.61 

26.81 

27.01 

27.21 

27.41 

27.61 

27.81 

28.01 

28.21 

28.41 

7.0 

26.85 

27.05 

27.25 

27.45 

27.65 

27.85 

28.05 

28.25 

28.45 

28.65 

7.2 

27.09 

27.29 

27.49 

27.69 

27.89 

28.09 

28.29 

28.49 

28.69 

28.89 

7.4 

27.33 

27.53 

27.73 

27.93 

28.13 

28.33 

28.53 

28.73 

28.93 

29.13 

7.6 

27.57 

27.77 

27.97 

28.17 

28.37 

28.57 

28.77 

28.97 

29.17 

29.37 

-7.8 

27.81 

28.01 

28.21 

28.41 

28.61 

28.81 

29.01 

29.21 

29.41 

29.61 

8.0 

28.05 

28.25 

28.45 

28.65 

28.85 

29.05 

29.25 

29.45 

29.65 

29.85 

8.2 

28.29 

28.49 

28.69 

28.89 

29.09 

29.29 

29.49 

29.69 

29.89- 

30.09 

8.4 

28.53 

28.73 

28.93 

29.13 

29.33 

29.53 

29.73 

29.93 

30.13 

30.33 

8.6 

28.77 

28.97 

29.17 

29.37 

29.57 

29.77 

29.97 

30.17 

30.37 

30.57 

8.8 

29.01 

29.21 

29.41 

29.61 

29.81 

30.01 

30.21 

30.41 

30.61 

30.81 

9.0 

29.25 

29.45 

29.65 

29.85 

30.05 

80.25 

30.45 

30.65 

30.85 

31.05 

9.2 

29.49 

29.69 

29.89 

30.09 

30.29 

80.49 

30.69 

30.89 

31.09 

31.29 

9.4 

29.73 

29.93 

30.13 

30.33 

30.53 

80.73 

30.93 

31.13 

31.33 

31.53 

9.6 

29.97 

30.17 

30.37 

30.57 

30.77 

80.97 

31.17 

31.37 

31.57 

31.77 

9.8 

30.21 

30.41 

30.61 

30.81 

31.01 

31.21 

31.41 

31.61 

31.81 

32.01 

10.0 

30.45 

30.65 

30.85 

31.05 

31.25 

31.45 

31.65 

31.85 

32.05 

32.25 

10.2 

30.69 

30.89 

31.09 

31.29 

31.49 

81.69 

31.89 

32.09 

32.29 

32.49 

10.4 

30.93 

31.13 

31.33 

31.53 

31.73 

81.93 

32.13 

32.33 

32.53 

32.73 

10.6 

31.17 

31.37 

31.57 

31.77 

31.97 

32.17 

32.37 

32.57 

32.77 

32.97 

10.8 

31.41 

31.61 

31.81 

32.01 

32.21 

32.41 

32.61 

32.81 

33.01 

33.21 

11.0 

31.65 

31.85 

32.05 

32.25 

32.45 

32.65 

32.85 

33.05 

33.25 

33.45 

11.2 

31.89 

32.09 

32.29 

32.49 

32.69 

32.89 

33.09 

33.29 

33.49 

33.69 

11.4 

32.13 

32.33 

32.53 

32.73 

32.93 

33.13 

33.33 

33.53 

33.73 

33.93 

11.6 

32.37 

32.57 

32.77 

32.97 

33.17 

33.37 

33.57 

33.77 

33.97 

34.17 

11.8 

32.61 

32.81 

33.01 

33.21 

33.41 

33.61 

33.81 

34.01 

34.21 

34.41 

CHEMICAL  TESTS  AND  ANALYSES  281 

GRAVIMETRIC  DETERMINATION 

Dilute  a  measured  portion  of  a  40  per  cent  solution  with  an 
equal  volume  of  water,  use  5  c.c.  of  the  diluted  mixture,  correspond- 
ing to  1  gram  of  the  evaporated  milk  and  proceed  as  directed  under 
"Milk,"  page  262. 

ASH 

Ignite  the  total  solids  at  very  low  redness,  cool,  weigh,  see 
"Milk,"  page  262. 

PROTEIDS 

Use  5  c.c.  of  a  40  per  cent  solution,  determine  nitrogen  accord- 
ing to  the  Gunning  method  as  directed  under  "Milk,"  page  262,  and 
multiply  result  by  6.38. 

LACTOSE 

Dilute  10  grams  of  a  40  per  cent  solution  to  about  40  c.c.  and 
add  .6  c.c.  of  Fehling's  copper  solution ;  nearly  neutralize  with 
sodium  hydroxide,  make  up  to  100  c.c.,  filter  through  dry  filter,  and 
determine  lactose  in  an  aliquot  as  directed  under  "Milk,"  page  266. 

FAT 
THE  MODIFIED  BABCOCK  METHOD1 

Carefully  weigh  4.5  grams  of  woll-mixed  evaporated  milk  into 
the  8  per  cent  test  bottle.  Add  one  17.6  c.c.  pipetteful  of  water.  Add 
17.5  c.c.  of  sulphuric  acid  and  shake  until  the  curd  in  the  test  bottle 
is  completely  dissolved.  Whirl  at  usual  speed  (one  thousand  revo- 
lutions per  minute)  for  five  minutes.  Mix  equal  portions  of  water 
and  sulphuric  acid  in  glass  beaker.  For  one  or  two  tests,  one 
pipetteful  of  water  and  one  acid  measure  full  of  acid  are  sufficient. 
Fill  test  bottle  to  slightly  below  the  bottom  of  the  neck  with  the  hot 
diluted  acid.  Whirl  for  two  minutes.  If  the  fat  collected  at  the 
base  of  the  neck  is  not  clear,  shake  the  bottle  until  all  the  curdy 
matter  is  completely  dissolved,  fill  the  bottle  to  about  the  8  per  cent 
mark  with  hot  water,  whirl  for  one  minute  and  read  the  test  at  135 
degrees  F.  The  fat  column  must  be  read  from  the  top  of  the  upper 
meniscus  to  the  bottom  of  the  lower  meniscus.  Multiply  the  reading 
by  4.  This  gives  the  correct  per  cent  of  fat. 

1  Hunziker  and   Spitzer,   Indiana  Agricultural   Experiment   Station.   Bulletin 
No.   134,   1909. 


282  CHEMICAL  TSSTS  AND  ANALYSES 

Instead  of  weighing  4.5  grams  into  the  test  bottle,  a  4.3  c.c 
pipette  may  be  used.     After  emptying  the  pipette  into  the  bottle  it 

should  be  rinsed  twice  and  the  rins- 
ings discharged  into  the  test  bottle. 

For  making  numerous  tests 
from  the  same  sample  it  is  advis- 
able to  dilute  the  evaporated  milk 
with  equal  parts  of  water,  by 
weight;  then  weigh  nine  grams  of 
this  dilution  into  the  test  bottle  and 
add  one-half  pipetteful  of  water. 

Read  from  A  to  D        TH*  RoSSE-GomiSB  METHOD 

Proceed  as  directed  under 
"Sweetened  Condensed  Milk,"  page 
274. 


Milk  Powder 

TOTAL  SOLIDS 

Weigh  5  grams  of  the  milk 
powder  in  a  drying  bottle  or  evap- 
orating dish  and  place  in  drying 

Reading  the9'  Bibcock  test      oven  at  100  to  105  degrees  C.  until 

constant  weight  is  secured. 

ASH 

Weigh  two  grams  of  the  milk  powder  in  a  weighed  platinum 
dish  and  proceed  as  directed  under  "Milk,"  page  262. 

PROTEIDS 

Use  five  grams  of  the  milk  powder  and  proceed  as  directed 
under  "Milk,"  page  262. 

MILK  SUGAR    (LACTOSE) 

Dissolve  ten  grams  of  milk  powder  in  90  c.c.  of  water.  Warm 
and  stir  until  a  satisfactory  solution  is  effected  and  proceed  as  di- 
rected under  "Milk,"  page  266,  and  multiply  result  by  10. 

SUCROSE 

For  the  determination  of  sucrose  proceed  as  directed  under 
"Sweetened  Condensed  Milk,"  page  275. 


THE:  MOJONNIER  TEST  283 

FAT 

THE;  BABCOCK  TEST  METHOD. — Dissolve  ten  grams  of  milk 
powder  in  90  c.c  of  water.  Warm  and  mix  until  a  complete  solu- 
tion is  effected.  Then  proceed  as  directed  under  "Milk,"  page  269, 
and  multiply  the  result  by  10. 

"RoESE-GoTTuEB  METHOD. — Weigh  one  gram  of  the  powder 
in  a  30  c-c.  lipped  beaker.  Rub  up  with  9  c.c.  of  water  and  2  c.c.  of 
concentrated  ammonium  hydroxid,  digest  on  steam  bath  until  the 
casein  is  well  softened  and  the  whole  resembles  milk.  Cool,  transfer 
to  Rohrig  tube  or  similar .  apparatus,  using  10  c.c.  of  95  per  cent 
alcohol  for  rinsing,  followed,  after  shaking  contents  of  tube,  by  25 
c.c.  of  washed  ethyl  ether.  Shake  vigorously  for  one-half  minute 
and  proceed  as  in  the  determination  of  fat  in  sweetened  condensed 
milk." 

CHAPTER  XXXII. 
THE  MOJONNIER  TEST  FOR  FAT  AND  SOLIDS  1 

The  Mojonnier  test  for  fat  and  solids  in  milk  and  milk  prod- 
ucts represents  the  use  of  chemical  apparatus  and  mechanical  de- 
vices of  a  high  degree  of  precision,  ingeniously  invented,  scientific- 
ally modified  and  especially  adapted  for  accurate  tests  of  dairy  prod- 
ucts. It  offers  methods  of  fat  and  solids  estimations  that  combine 
the  accuracy  of  official  chemical  analysis  with  the  rapidity  of  fac- 
tory tests.  It  has  been  introduced  in  and  is  successfully  used  by 
most  of  the  progressive  milk-condensing  factories  in  the  country, 
and  it  is  admirably  filling  a  long-felt  demand  for  reliable  and  accu- 
rate methods  of  testing  milk,  condensed  milks  and  milk  powders 
and  for  standardizing  these  products  under  factory  conditions. 


1  Directions  furnished  through  courtesy  of  Mojonnier  Bros.  Co.,  Milk  Engi- 
neers,  Chicago. 


284  THE:  MOJONNIER 

8        5        3031    25  II  7      10     3   136    4 


17 


24 


16  29  14         15    19         18 

Fig.  66.     The  Mojonnier  tester 
Courtesy  of  Mojonnier  Bros.  Company 

EQUIPMENT 

Install  the  tester  on  a  solid  foundation  in  a  room  protected 
against  excessive  fluctuations  in  temperature. 

1.  Tester  for  butter  fat. 

2.  Tester  for  total  solids. 

3.  Fat  extraction  flasks. 

4.  Eight  3^ -inch  aluminum  dishes  without  covers  and  with 
tall  counterpoise  which  tares  the  eight  dishes,  for  fat  tests. 

5.  Eight  3-inch  aluminum  dishes  with  covers  and  short  coun- 
terpoise, for  solids  tests. 

6-     Fat  oven.    Keep  temperature  at  135°  C. 

7.  Cooling  chamber. 

8.  Solids  oven.     Keep  temperature  at  100°  C. 

9.  250°  C.  thermometer  for  solids  oven.    Have  mercury  bulb 
fit  snugly  into  brass  mercury  well.    Brass  mercury  well  must  always 
form  good  contact  with  hot  plate- 


THE  MOJONNIER  TEST  285 

10.  250°  C.  thermometer  for  fat  oven.    Observe  same  precau- 
tions as  in  (9). 

11.  Vacuum  gauge  on  main  suction  line,  registers  either  or 
both  ovens. 

12.  Solids  plate.    Must  be  level  and  held  at  180°  C. 

13.  Fat  plate.    Hold  at  135°  C. 

14.  Rheostat  for  fat  plate.     Lever  must  make  good  contact 
with  one  button,  not  with  two  at  a  time.    When  right  button  has  been 
found  that  maintains  constant  temperature,  mark  this  point  on  rheo- 
stat rim.     When  starting  tester  each  day,  turn  handle  on  full  until 
temperature  has  risen  to  within  right  point,  then  turn  back  to  previ- 
ously marked  button. 

15.  Rheostat  for  oven.    Observe  same  precautions  as  in  (14). 

16.  Rheostat  for  solids  oven.     Observe  same  precautions  as 
in  (14). 

17.  Rheostat  for  solids  plate.     Observe  same  precautions  as 
in  (14). 

18.  Handle  for  centrifuge. 

19.  Snap  switches  for  each  hot  plate  showing  temperature  and 
time  for  treating  samples  at  various  points. 

20.  Power  unit,  consisting  of  vacuum  pump,  water  circulating 
pump  and  motor  for  same.     Keep  pump  filled  to  air  cock  with  oil 
furnished  with  tester. 

21.  Automatic  burettes  and  cans  holding  the  water,  ammonia, 
alcohol,  ethyl  ether  and  petroleum  ether,  placed  in  the  order  in  which 
they  are  used.     Each  division  on  burettes  delivers  the  proper  amount 
of  the  desired  reagent  for  a  single  extraction. 

22.  Hood,  to  be  placed  over  fat  dishes  when  evaporating  off 
ether- 

23.  Legs,  to  be  fastened  to  floor  with  lag  screws. 

24.  This  side  need  not  be  fastened  to  floor.     If  necessary  to 
take  out  power  unit  disconnect  connections  in  rear  of  machine  and 
move  this  part  of  machine  forward. 

25.  Chemical  balance.    Keep  level,  clean  and  handle  carefully. 
Raise  knife  edges  gradually  and  with  care.     Clean  balance  daily. 
Keep  weights  clean.    When  weights  show  signs  of  wear,  order  new 
ones. 

26.  Cock,  to  exhaust  vacuum  from  oven  when  cock  (27)  is 
closed.    Must  be  kept  closed  when  vacuum  is  turned  on  oven. 


286  THE:  MOJONNIKR  TEST 

27.  Cock,  that  switches  vacuum  from  main  line  into  vacuum 
oven.     Set  of  cocks  at  right  is  for  solids  oven,  set  of  cocks  at  left 
is  for  fat  oven- 

28.  Hole  in  top  of  fat  plate  holder,  communicating  with  suction 
fan,  on  power  unit.    Run  exhaust  pipe  on  suction  fan  out  of  window 
and  keep  hood  over  the  dishes  in  order  to  drive  all  ether  fumes 
from  room. 

29.  Stool,  to  be  screwed  to  floor. 

DIRECTIONS  FOR  OPERATING  MOJONNIER  TEST 

Preliminary  directions  for  tests  of  both  Fat  and  Solids.     (See 
also  list  of  precautions  appended,  pp.  292-294. 

(1)  Wash  solids  dishes  with  warm  water  and  fat  dishes  with 
gasoline.    Dry  with  a  towel  and  place  into  heated  vacuum  oven  for 
five  minutes  with  vacuum  on.    At  the  end  of  five  minutes  put  these 
dishes  into  cooler  and,  with  the  pump  still  running,  keep  them  there 
for  five  minutes  before  weighing.     Do  not  turn  off  motor  until  last 
dish  is  weighed  out  of  cooling  chamber. 

(2)  While  dishes  are  being  heated  and  cooled,  wash  pipettes 
with  water,  alcohol  and  ether  and  dry  by  applying  vacuum  at  ex- 
haust cock  upon  tester.     Always  use  clean  and  dry  pipettes  for  each 
different  sample.     Aim  to  clean  pipettes  as  well  as  all  glassware, 
immediately  after  using. 

(3)  It  is  very  important  to  keep  extraction  flasks  clean.   Wash 
these   with   warm  water  immediately  after  extraction   is   finished. 
Wash  with  washing  powder  and  shot  when  necessary. 

(4)  After  aluminum  dishes  have  been  in  cooler  for  at  least 
five  minutes,  weigh  accurately  to  .0001  gram,  using  the  proper  coun- 
terpoise.    Weigh  solids  dishes  with  cover  on.     Fat  dishes  do  not 
have  covers.     Fat  dishes  should  be  cooled  for  seven  minutes  before 
being  weighed. 

( 5 )  Use  weighing  pipettes  as  follows :     Fill  five-gram  pipette 
up  to  five-gram  mark  for  butter  fat,  and  one-gram  pipette  up  to  one- 
gram  mark  for  total  solids.     If  duplicates  are  to  be  run  fill  two 
pipettes  from  the  same  sample.     As  pipettes  are  filled  place  lower 
end  into  cleaned   and   dry  rubber  tubes   which   are   pressed   upon 
knobs  at  ends  and  center  of  weighing  cross.     Either  five  or  less 
samples    for   butter    fat  or   five    or  less  for    total    solids    m'ay  be 
pipetted  out. 


THE  MOJONNISR  TEST  287 

(6)  Weigh  the  cross  with  the  pipettes  containing  the  milk  on 
chemical  balance  accurately  to  .0001  grairu  Run  milk  from  pipette 
into  proper  flask,  or  3-inch  dish  if  making  solids  test.  The  pipettes 
may  be  distinguished  by  the  number  upon  each  cross.  Replace 
pipette  and  weigh  again.  Difference  in  weight  gives  weight  of  sam- 
ple. Repeat  until  all  samples  are  run  into  proper  flasks,  and  into 
weighed  solids  dishes  if  solids  are  determined  along  with  the  fat. 

For  fat  in  Sweetened  Condensed  Milk  use  a  five-gram  sample. 
The  five-gram  pipette  delivers  approximately  five  grams  between 
the  five-gram  mark  and  the  base  of  the  bowl  of  the  pipette- 

Some  operators  prefer  to  mix  200  grams  of  sweetened  con- 
densed milk  with  200  grams  of  water,  weighing  these  carefully  upon 
a  Harvard  trip  scale  sensitive  to  .1  gram.  In  this  case  care  must  be 
exercised  to  obtain  the  exact  weight  of  both  milk  and  water  and  to 
stir  these  thoroughly  with  glass  or  metal  rod  before  taking  sample. 
A  tall  tumbler,  a  one-pound  bottle  or  a  quart  cup  make  good  con- 
tainers in  which  to  make  mixture.  A  ten-gram  sample  of  this  mix- 
ture is  used.  This  is  best  weighed  out  by  using  two  five-gram 
pipettes  on  weighing  cross. 

For  total  solids  weigh  out  y2  (.5000)  to  ft  (.7500)  gram  of 
this  mixture.  If  the  undiluted  milk  is  used  take  as  nearly  (.2500) 
gram  as  possible. 

For  regular  8  per  cent  plain  bulk  condensed  milk  use  same  size 
samples  and  treat  same  as  evaporated  milk.  For  12  per  cent  super- 
heated condensed  milk  mix  100  grams  milk  with  300  grams  water 
upon  Harvard  trip  scale.  Weigh  ten-gram  sample  of  this  mixture 
into  flask  for  fat  and  a  two-gram  sample  into  solids  dish  for  solids. 
Multiply  percentages  obtained  by  four  for  correct  percentages,  when 
a  1  to  4  dilution  is  made- 

FRESH  MILK,  SKIM  MILK,  WHEY,  BUTTERMILK 

BUTTER  FAT  DETERMINATION 

(1)  Use  the  ten-gram  pipettes  for  measuring  out  ten  grams 
of  milk  into  cleaned  but  not  necessarily  dried  Mojonnier  extraction 
flask.  Use  only  ten-gram  pipettes  furnished  with  tester  and  do  not 
use  10  c.c-  pipettes.  The  pipette  is  graduated  to  deliver  ten  grams 
of  milk  after  allowing  all  milk  to  run  out  and  letting  it  drain  for 
fifteen  seconds  longer,  then  blowing  gently  to  remove  last  drop. 


288  THE;  MOJONNISR  TEST 

The  pipette  must  be  perfectly  clean  and  dry  before  being  used. 
Wash  frequently  with  sulphuric  acid,  water,  alcohol  and  ether  to 
insure  having  a  clean  pipette. 

(2)  Make  extractions  exactly  as  in  test  for  butter  fat  in  con- 
densed milk,  excepting  that  in  second  extraction  only  15  c.c.  of  each 
ether  need  be  used. 

(3)  Percentage    butter    fat    is    obtained   by    multiplying   the 
weight  of  the  extracted  butter  fat  by  10. 

(4)  If  any  of  these  products  have  soured  badly,  double  the 
quantity  of  ammonia  in  the  regular  extraction  and  shake  until  all 
particles  are  dissolved. 

TOTAL  SOLIDS  DETERMINATION 

(1)  Determine  total  solids  as  in  evaporated  milk,  excepting 
that  a  two-gram  sample  is  weighed  out,  and  no  water  need  be  added 
to  spread  the  milk  over  the  bottom  of  the  dish. 

SWEETENED  CONDENSED  MILK,  EVAPORATED  MILK 
AND  CONDENSED  BULK  MILK 

BUTTER  FAT  DETERMINATION 

(1)  Remove    flask  from    holder    and  run  4  c.c.    water   (one 
charge  on  water  burette)   into  each  flask.     Be  careful  not  to  add 
more.     vShake  well  until  all  of  sample  is  mixed  with  water.     This 
can  be  done  without  inserting  cork. 

For  Sweetened  Condensed  Milk,  if  not  diluted  with  water,  add 
6  c.c.  of  hot  water  with  a  pipette.  To  get  hot  water  place  fat  dish 
filled  with  distilled  water  upon  solids  plate.  If  sweetened  milk  has 
been  previously  diluted  with  water  and  a  ten-gram  sample  has  been 
used,  it  is  not  necessary  to  add  water- 

It  is  very  necessary  to  shake  the  flasks  containing  the  sweet- 
ened condensed  milk  very  thoroughly  after  the  addition  of  each 
reagent.  Sweetened  condensed  milk  requires  more  shaking  than 
any  other  liquid  milk  product. 

(2)  Before  replacing  flask  into  holder,  add  \y2  c.c.  c.p.  am- 
monia.    Shake  well  so  that  all  of  sample  is  well  mixed  with  am- 
monia.    This  can  be  done  without  inserting  cork. 

(3)  Add  95  per  cent  alcohol  up  to  base  of  top  bulb  of  extrac- 
tion  flask.     Insert   cork,   using  best   quality   corks   only.     Replace 


THE  MOJONNISR  TEST  289 

flask  into  flask  holder.  Shake  thoroughly  and  see  that  no  milk  ad- 
heres to  any  part  of  flask  undissolved.  In  case  particles  of  milk 
stick  to  side  of  flask,  shake  thoroughly  until  these  are  washed  away. 
It  is  of  the  utmost  importance  to  shake  thoroughly  at  this  point. 

(4)  Add  25  c.c.  ethyl  ether,  insert  corks  and  shake  vigorously, 
lengthwise  of  flask,  with  liquid  in  large  bulb  of  flask,  and  small  bulb 
extended  upward-     Stop  shaking  at  end  of  five  seconds  until  all 
liquid  has  run  into  large  bulb  and  repeat  vigorous  shaking  for  four 
five-second  periods. 

(5)  Add  25  c.c.  petroleum  ether  and  shake  in  same  way. 

(6)  Place  extraction    flasks  into    centrifuge    and  whirl    for 
thirty  turns  at  speed  of  about  600  R.  P.  M.     Double  time  for  sweet- 
ened condensed  milk. 

(7)  Place  four  3^-inch  dishes  in  line  on  shelf  adjoining  hot 
plate,  keeping  them  in  order  in  which  their  weights  were  posted 
upon  record  sheet.     Aim  to  have  numbers  on  flasks  correspond  with 
number  of  dishes. 

(8)  Pour    ether    extraction    to    dividing    line    into    proper 
dishes  and  slide  dishes  over  onto  hot  plate,  which  should  be  held 
at  a  temperature  of  135  degrees  C.,  as  indicated  by  thermometer  in- 
serted in  nickel  plated  mercury  well. 

(9)  Repeat   the   extraction,   adding   first   alcohol    enough   to 
bring  line  close  up  to  top  of  small  neck  of  flask,  then  25  c.c.  ethyl 
ether,  and  then  25  c-c.  petroleum  ether,  and  shake  vigorously  after 
the  addition  of   each  of  above  three  reagents   for   four   5-second 
periods. 

(10)  Whirl  in  centrifuge  for  thirty  turns. 

(11)  Move  aluminum  dishes  back  upon  shelf  adjoining  hot 
plate  and  pour  the  second  extraction  into  proper  dishes.     Never 
pour  extraction  into  hot  dish.     Remove  dish  from  hot  plate  as  soon 
as  ether  is  all  evaporated. 

(12)  When  all    of  ether  has    evaporated    place    dishes  into 
vacuum  oven,  which  should  have  a  temperature  of  135  degrees  cen- 
trigrade.     Keep  them  there  for  five  minutes  after  the  vacuum  gauge 
shows  at  least  twenty-two  inches  of  vacuum. 

(13)  Place  "dishes  into  cooler  for  seven  minutes,  with  pump 
outfit  running.     See  that  water  is  running  through  cooling  plates. 


290  THE:  MOJONNIER  TEST 

(14)  Place  counterpoise  for  dish  and  the  approximate  weight 
for  fat  on  right  hand  balance  pan. 

(15)  Transfer  dish  to  left  hand  balance  pan  and  weigh  quickly 
to  0.10  milligram   (0.0001  gr.). 

(16)  Weight  of  fat  divided 'by  weight  of  sample  taken,  mul- 
tiplied by  100,  represents  per  cent  butter  fat. 

TOTAL  SOLIDS  DETERMINATION 

(1)  The  temperature  of  the  hot  plate  in  the  solids  vacuum 
oven  must  be  100  degrees  C.     The  temperature  of  the  outside  solids 
plate  must  be  170  degrees  to  180  degrees  C. 

(2)  To  weighed  milk  in  solids  dish  add  about  1  c-c.  water  and 
distribute  mixture  evenly  over  bottom  of  dish.     For  sweetened  con- 
densed milk  use  hot  water. 

(3)  Place  not  more  than  two  dishes  at  once  upon  hot  plate, 
which  must  be  perfectly  level.     Allow  all  visible  moisture  to  evap- 
orate.    During  the  evaporation  turn  the  dishes  around  with  crucible 
tongs,  slowly,  so  as  to  produce  an  even  boiling  over  the  whole  bot- 
tom surface  of  the  dishes.     The  dishes  must  be  watched  carefully 
during  the  evaporation.     This  step  should  require  not  more  than 
two  minutes.     The  end  point  is  reached  when  bubbling  and  crack- 
ling ceases  and  sample  shows  first  trace  of  brown.     Vigorous  boil- 
ing without  spattering  and  complete  evaporation  are  fundamentally 
essential. 

(4)  Place  dishes  into  vacuum  oven,  which  must  be  at  100  de- 
grees C.,  and  turn  on  the  vacuum.     Heat  for  ten  minutes.     In  the 
case  of  sweetened  condensed  milk  keep  it  for  twenty  minutes  in 
vacuum  oven.     The  gauge  should  register  not  less  than  twenty-two 
inches  of  vacuum.     If  for  any  reason  you  cannot  obtain  at  least 
twenty-two  inches  of  vacuum  then  leave  dishes  in  oven  for  twice 
the  regular  time. 

(5)  Remove  from  oven  and  place  into  cooler.     Allow  dishes 
to  cool  for  five  minutes. 

(6)  Weigh  dishes  with  covers  on  in  the  same  manner  that 
the  butter  fat  dishes  were  weighed,  being  careful  to  weigh  quickly 
and  very  exactly- 

(7)  Weight  of  dry  solids  divided  by  weight  of  milk  taken, 
multiplied  by  100,  represents  per  cent  total  solids. 


THE  MOJONNIER  TEST  291 

POWDERED   MILK  AND   MALTED   MILK 
Method  of  Sampling 

Mix  the  sample  thoroughly,  making  sure  that  it  is  sufficiently 
pulverized  and  representative  of  the  entire  lot  to  be  tested.  Trans- 
fer the  pulverized  sample  promptly  to  a  sealed  jar.  Mix  before 
removing  portions  for  testing. 

BUTTER  FAT  DETERMINATION 

(1)  Weigh   out   rapidly,   to  prevent   absorption   of   moisture 
from  the  air,  about  one  gram  of  milk  powder  into  butter  boat.     In 
case  of  malted  milk,  weigh  out  a  0.5  gram  sample. 

(2)  Add  8.5  c.c.  of  hot  water  to  flask.     Insert  cork.     Heat 
flask  in  water  boat  and  shake  thoroughly  until  the  sample  is  well 
mixed. 

(3)  Add    1.5   c.c.    (one   charge)    ammonia,   and   shake   thor- 
oughly- 

(4)  Add  alcohol  up  to  line  on  small  neck  of  flask.     Insert 
cork.     Replace  flask  into  flask  holder.     Shake  flask  thoroughly  with 
cork  inserted.     Use  best  quality  cork  only. 

(5)  Cool  flask  by  running  cold  water  over  lower  end  of  ex- 
traction flask,  if  flask  is  very  hot.     This  is  not  ordinarily  necessary. 

(6)  Add  25  c.c.  ethyl  ether.     Insert  corks,  shake  vigorously 
until  all  butter  is  dissolved  out  of  boat.     Then  add  25  c.c-  petroleum 
ether  and  repeat  operation. 

(7)  Centrifuge  flasks,  turning  handle  thirty  turns  after  cen- 
trifuge has  reached  a  speed  of  about  600  R.  P.  M. 

(8)  Pour  off  extractions  into  proper  weighed  3^-inch  alum- 
inum dishes.     Repeat  above  extraction,  adding  first  alcohol,  then 
25  c.c.  of  each  ether.     Excepting  for  very  accurate  work  a  third 
extraction  is  not  necessary. 

The  second  extraction  will  remove  all  but  .10  to  .15  per  cent 
of  the  butter  fat.  For  factory  control  work  this  would  be  a  good 
margin  of  safety. 

(9)  Evaporate  off  ether  at  135  degrees  C.  on  "fat  plate,"  and 
when  all  of  ether  is  off,  dry  fat  in  fat  oven  held  at  135  degrees  C. 
for  five  minutes  after  the  vacuum  has  reached  at  least  twenty-two 
inches. 

(10)  Cool,  weigh  and  calculate  per  cent  butter  fat. 


292  THE  MOJONNIER  TEST 

TOTAL  SOLIDS  DETERMINATION 

(1)  Use  .3000  gram  sample-     Add  2  c.c.  distilled  water  to 
the  sample  in  this  dish.     Mix  milk  powder  and  water  thoroughly 
with  the  blunt  rod. 

(2)  Continue  the    determination  as  under    evaporated    milk, 
but  continue  heating  in  the  vacuum  oven  for  twenty  minutes. 

LIST  OF  PRECAUTIONS  TO  OBSERVE  IN  OPERATING 
MOJONNIER  TESTER 

(1)  Before  the  reagents  are  put  into  the  cans  be  sure  that 
the  cans  are  thoroughly  cleaned  by  washing  all  parts  first  with  warm 
water,  then  alcohol  and  then  ether.     Every  third  or  fourth  time 
cans  are  filled,  empty  out  last  portion  of  reagents  and  use  for  clean- 
ing purposes. 

(2)  The  bottom  of  all  dishes  should  be  kept  as  flat  as  possible. 
Any  bulging  may  be  worked  out  by  resting  dishes  upon  marble  plate 
in  front  of  balance,  rubbing  entire  bottom   surface  with  thumbs. 
Operator  should  observe  this  every  time  dishes  are  cleaned.     This 
is  very  important. 

(3)  The  calcium  chloride  in  the  coolers  should  be  changed 
every  three  or  four  weeks.     The  same  calcium  chloride  may  be 
used  over  and  over  by  drying  the  used  calcium  chloride  in  the  tin 
dishes  placed  upon  hot  plates  held  at  135  degrees  centigrade  for 
at  least  5  hours. 

(4)  The  bottles  should  be  whirled  in  the  centrifuge  until  the 
ether  extraction  is  perfectly  clear.     About  30  turns  at  a  normal 
speed  is  to  be  recommended.     For  sweetened  condensed  milk  this 
time  must  be  doubled. 

(5)  Be  sure  to  keep  extraction  flasks  perfectly  clean.     Wash 
often  with  sulphuric  acid  and  washing  powder,  if  necessary.     If 
particles  cling  to  the  sides  put  in  small  shot,  washing  powder,  and 
hot  water  and  shake  thoroughly. 

(6)  Keep  temperature  regulated  as  nearly  to  standard  tem- 
perature as  possible. 

(7)  Never  pour  off  extraction  into  a  hot  dish.     Remove  dish 
from  plate  before  second  extraction  is  run  into  dish- 


THE  MOJONNIER  TEST  293 

(8)  Be  careful  to  pour  off  ether  into  dishes  slowly  at  first 
and  gradually  increase  stream  until  full  stream  is  running. 

(9)  In  using  weighing  pipettes  make  sure  that  neck  of  flask 
is  free  from  water  when  pipette  is  inserted. 

(10)  Always  use  clean  and  dried  pipettes. 

(11)  If  the  samples  for  solids  have  to  stand  for  any  length 
of  time  add  the  water  just  as  soon  as  they  are  measured  out,  other- 
wise there  is  a  tendency  to  dry  and  a  good  mixture  with  the  water 
cannot  be  obtained.     Keep  dishes  upon  marble  plate  beside  the  bal- 
ance, and  not  on  hot  plate  support. 

(12)  Redistill   ether   and   petroleum   ether,    unless   they   are 
known  to  be  pure.     This  is  unnecessary  if  these  are  bought  from 
a  reliable  firm. 

(13)  Make  sure  that  water  is  always  running  through  cooling 
plate.    Watch  pipe  back  of  cooler.    If  tester  is  located  in  cold  room 
in  winter  add  a  gallon  of   denatured  alcohol  to  tank  to  prevent 
freezing. 

(14)  Always  aim  to  weigh  empty  dishes  just  before  you  are 
ready  to  use  them.     It  is  not  advisable  to  weigh  them  a  long  time 
before  they  are  used. 

(15)  It  is  fundamentally  important  to  see  that  weights  are 
read  and  posted  rightly.  Operator  should  keep  his  weights  in  syste- 
matic, order  upon  balance  pan.     When  a  reading  is  taken  it  should 
be  checked  at  least  three  times.     Learn  to  make  weighings  abso- 
lutely right. 

(16)  Every  operator  should  from  time  to  time  have  a  sample 
checked  by  a  thoroughly  reliable  laboratory. 

//  results  on  fat  are  high  as  compared  with  check  results,  the 
cause  may  be  one  of  the  following : 

(a)  Not  keeping  bottom  of  dishes  flat. 

(b)  Improper  shaking  and  centrifuging  shown  by  non-fatty 
residue  in  dish. 

(c)  Improper  reagents   (if  in  doubt  run  test  upon  reagents 
substituting  water  for  milk). 

(d)  Temperature  in  fat  oven  too  low. 

(e)  Dirt  has  gotten  into  dish  after  ether  was  poured  into  it. 

(f)  Improper  reading  or  posting  of  weights.     Weights  have 
lost  weight  from  use. 


294  THE;  MOJONNIER  TEST 

//  results  on  fat  are  lozv  as  compared  with  check  results  the 
cause  may  be  one  of  the  following: 

(a)  Leaky  corks.    Use  best  corks  obtainable. 

(b)  Insufficient  shaking. 

(c)  Adding  too  much  water. 

(d)  Having  dividing  line  too  low,  so  that  too  much  ether  is 
left  behind.     If  such  is  the  case  add  distilled  water  to  bring  line  to 
the  proper  height  or  make  a  third  extraction. 

(e)  Too  high  temperature  in  vacuum  oven- 

(f)  Not  having  water  running  through  cooler.     Tank  must 
be  kept  filled. 

(g)  Improper  reading  or  posting  of  weights. 

//  results  on  total  solids  are  too  high,  as  compared  to  check 
results  the  cause  may  be  one  of  the  following: 

(1)  Bottoms  of  dishes  are  not  kept  flat. 

(2)  Evaporation  upon  solids  plate  has  not  been  carried  far 
enough.     Be  sure  to  manipulate  dish  so  that  vigorous  boiling  takes 
place  upon  the  entire  surface  of  the  bottom  of  the  dish.     Do  not 
remove  dish  until  all  visible  moisture  is  off  or  until  first  trace  of 
brown  coloration  appears. 

(3)  Improper  reading  or  recording  of  weights.    Weights  have 
lost  weight  from  use. 

(4)  Dirt  has  fallen  into  dish  after  sample  has  been  weighed 
into  it. 

(5)  Temperature  in  vacuum  oven  is  too  low. 

(6)  Vacuum  is  not  up  to  standard. 

//  results  on  total  solids  are  too  low,  the  cause  may  be  one  of 
the  following: 

(1)  Sample  is  browned  too  much  upon  outside  hot  plate. 

(2)  Temperature  in  vacuum  oven  is  above  105  degrees  C. 

(3)  Milk  spattered  from  dish.     This  will  not  happen  if  tem- 
perature is  kept  at  180  degrees  C. 

(4)  Improper  reading  or  recording  of  weights. 

(5)  Water  is  not  running  through  cooler- 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES         295 

CHAPTER  XXXIII. 

DETECTION  OF  ADULTERANTS  AND   PRESERVATIVES 

IN  MILK 

Addition  of  Water  and  Skim  Milk  and  the  Removal  of  Cream 

FREQUENCY  OF  ADULTERATION. — Experience  has  shown  that 
where  milk  is  received  from  a  large  number  of  patrons,  as  is  the 
case  in  most  milk  condensing  factories,  some  of  the  milk  may  be  and 
frequently  is  being  tampered  with  before  it  reaches  the  factory. 
In  the  case  of  condenseries  buying  and  paying  for  the  milk  on  the 
butter  fat  basis,  neither  the  watering  nor  the  skimming  of  the  milk 
results  in  any  material  direct  loss  to  the  factory.  Excessive  skim- 
ming, however,  does  reduce  the  yield  of  the  finished  product  some- 
what, inasmuch  as  a  small  amount  of  solids  is  removed  with  the 
cream.  Excessive  watering  necessitates  the  expenditure  of  slightly 
more  fuel  to  remove  the  extraneous  water  in  the  process  of.  evap- 
oration. 

Where  the  condensery  buys  and  pays  for  its  milk  by  the  hun- 
dred weight,  however,  it  is  obviously  essential  that  such  adultera- 
tions be  guarded  against  by  eternal  vigilance. 

TAKING  AND  PRESERVING  OF  THE  SAMPLE. — In  order  to  min- 
imize the  work  of  testing  without  interfering  with  the  effectiveness 
of  the  control,  it  is  advisable  to  take  composite  samples.  Use  pint 
jars  with  tight  lids ;  label  the  jars  with  the  number  of  the  respective 
patron  and  place  them  in  numerical  order  on  conveniently  located 
shelves  on  the  receiving  platform.  In  the  case  of  the  route  system 
of  receiving  milk,  the  samples  of  milk  from  each  route  should  be 
stored  together.  Use  a  dipper  holding  one  ounce  of  milk ;  by  pour- 
ing a  dipperful  of  milk  of  each  patron  each  day  into  the  respective 
jars,  enough  milk  is  collected  in  each  jar  at  the  end  of  two  weeks 
to  test  with  the  lactometer  and  the  Babcock  tester  every  two  weeks. 

In  order  to  preserve  the  samples  in  proper  condition  drop  a 
large  corrosive  sublimate  tablet  into  each  empty  jar  and  after  each 
addition  of  milk,  mix  the  corrosive  sublimate  with  the  milk  by 
giving  the  jar  a  rotary  motion.  Add  one  dipperful  of  each  patron's 
milk  daily  into  the  jars. 

TESTING  THE  COMPOSITE  SAMPLES. — At  the  end  of  every  two 
weeks  test  the  samples  with  the  Quevenne  lactometer  and  the  Bab- 


296         DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES 

cock  test.  The  samples  should  have  a  temperature  of  55  to  65  de- 
grees F.  In  summer  and  at  any  other  time  when  the  temperature 
naturally  is  much  higher  or  lower,  place  the  sample  jars  into  a  tank 
or  tub  of  water  at  the  desired  temperature,  from  one-half  hour  to 
an  hour  before  testing.  For  directions  for  the  use  of  the  lactom- 
eter and  the  Babcock  tester,  see  "Milk,"  Chapter  XXXI,  page  262. 
If  the  milk  contains  corrosive  sublimate,  deduct  one-half  point  from 
the  lactometer  reading  for  each  tablet  in  one  pint  of  sample. 

INTERPRETATION  OF  RESULTS. — The  lactometer  reading  and  the 
per  cent  fat  alone  furnish  a  pretty  safe  index  to  the  freedom  from, 
or  presence  of  adulteration  of  the  milk.  From  these  two  factors 
other  guides,  such  as  the  specific  gravity,  per  cent  of  total  solids 
and  per  cent  of  solids  not  fat  of  milk,  and  specific  gravity  of  the 
milk  solids  may  be  calculated.  These  are  of  additional  assistance  to 
the  inspector.  All  of  these  factors  vary  considerably  with  the  indi- 
viduality, breed,  period  of  lactation  and  feed  of  the  cows,  so  that 
considerable  latitude  must  be  allowed  in  determining  whether  or  not 
any  given  sample  of  milk  has  been  adulterated.  These  variations 
are  greatest  between  individual  cows  and  between  different  breeds, 
but  they  also  are  quite  striking  in  milk  of  the  same  cows  from  day 
to  day  and  at  different  stages  of  the  period  of  lactation.  In  mixed 
herd  milk,  such  as  the  condensery  largely  receives,  the  composition 
is  comparatively  uniform  on  consecutive  days.  Whenever  possible, 
in  the  case  of  suspicious  milk  received  at  the  factory,  samples 
should  be  secured  direct  from  the  stable  for  comparison. 

The  following  may  be  considered  reasonable  limits  of  compo- 
sition beyond  which  normal  milk  seldom  trespasses,  and  milk  not 
falling  within  these  limits  may  be  regarded  with  suspicion. 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES 


297 


Minimum 

Per  Cent  Fat.  2.5 

Specific  gravity  of  milk     1-029 
Per  cent  total  solids         11.50 
Per  cent  solids  not  fat     7.75 
Specific  gravity  of  milk 

solids  1.25 

These  factors  are  affected  by  the  skimming  and  watering  of 
milk  as  follows : 

Fat  low 

Cream  removed  or 


Maximum 

Average 

4 

1.034 

1.032 

12.3 

9.25 

8.5 

1.36 

1.33 

skim  milk  added 


Specific  gravity  of  milk  high 


Water  added 


Total  solids  low 

Solids  not  fat  high 

Specific  gravity  of  milk  solids  high 

Fat  normal  or  loiv 

Specific  gravity  of  milk  low 

Total  solids  low 

Solids  not  fat  low 

Specific  gravity  of  milk  solids  normal 

Fat  low 

Specific  gravity  of  milk  normal 
Total  solids  low 
Solids  not  fat  lo^v  or  normal 
Specific  gravity  of  milk  solids  normal  or  high 
The  total  solids  are  determined  by  the  formula: 

-^-+  1-2  X  f. 


Cream  removed 
and  water  added 


The  solids  not  fat  are  determined  by  the  formula 


The  specific  gravity  of  the  milk  solids  is  determined  by  the 
formula 


t_  100s— 100 


298         DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES 

L,  =  Quevenne  lactometer  reading  at  60  degrees  F. ;  f  =  per 
cent  fat ;  t  =  total  solids ;  s  =  specific  gravity  of  milk. 

Example  of  milk  that  is  normal — Quevenne  lactometer  reading 
at  60  degrees  F.  32,  fat  4  per  cent. 

Answer : 

Specific  gravity  of  the  milk  =  1.032 

Total  solids   -^--+ 1.2  X  4=  12.8  per  cent. 

32 
Solids  not  fat  — 1-  .2  X  4  =  8.8  per  cent. 

Specific  gravity  of  milk  solids 
12.8 


12.8— 100  X  1.032—100=  1.32 


1.032 

Example  of  milk  to  which  water  has  been  added. — Quevenne 
lactometer  reading  at  60  degrees  F.  26,  fat  3.8  per  cent. 

Answer : 

Specific  gravity  of  milk  =  1.026 

Total  solids—^--  +  1.2  X  3.8  =  11.06  per  cent. 

26 
Solids  not  fat  — —  +  .2  X  3.8  —  7.26  per  cent. 

Specific  gravity  of  milk  solids 
11.06 


11.06—  100  X  1.026—100=  1.295 


1.026 

Example  of  milk  from  which  cream  was  removed  or  to  which 
skimmed  milk  was  added. — Quevenne  lactometer  reading  at  60  de- 
grees F.  35,  fat  2  per  cent. 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES          299 

Answer : 

Specific  gravity  of  milk  =  1.035 

Total  solids. — \-l2X  2=  11.15  per  cent. 

Solids  not  fat  ~—  +  .2  X  2  =  9.15  per  cent. 

Specific  gravity  of  milk  solids 
11.15 


11.15  — 100  X  1.035  —  ICO  —  1.446 


1.035 

llxample  of  milk  from  which  cream  was  removed  and  to  which 
r  was  added. — Quevenne  lactometer  reading  at  60  degrees  F. 
32,  fat  2  per  cent. 

Specific  gravity  of  milk  =•  1.032 

Total  solids  ^~-+  1.2  X  2  =10.4  per  cent. 

3? 
Solids  not  fat  —^ 1-  .2  X  2  =  8.4  per  cent. 

Specific  gravity  of  milk  solids 
10.4 


10.4  —  100  X  1.032  —  100  =  1.425  per  cent. 
1.032 


300         DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES 

Determination  of  Added  Water  by  the  Acetic  Serum — the  Sour 
Serum — and  the  Copper  Serum  Methods  ^ 

ACETIC  SERUM.— TENTATIVE 

"(a)  Zeiss  immersion  refractometer  reading. — To  100  c.c.  of 
milk  at  a  temperature  of  about  20°  C.  add  2  c.c.  of  25  per  cent  acetic 
acid  (sp.  gr.  1.035)  in  a  beaker  and  heat  the  mixture,  covered  with 
a  watch  glass,  in  a  water  bath  for  twenty  minutes  at  a  temperature 
of  70°  C.  Place  the  beaker  on  ice  water  for  ten  minutes  and  sepa- 
rate the  curd  from  the  serum  by  filtering  through  a  12.5  cm.,  folded 
filter.  Transfer  about  35  c.c.  of  the  serum  to  one  of  the  beakers  that 
accompanies  the  control-temperature  bath  used  in  connection  with 
the  Zeiss  immersion  refractometer,  and  take  the  refractometer  read- 
ing at  exactly  20°  C.,  using  a  thermometer  graduated  to  tenths  of  a 
degree.  A  reading  below  39  indicates  added  water ;  between  39 
and  40,  the  addition  of  water  is  suspected. 

(b)  Ash. — Transfer  25  c.c-  of  the  serum  to  a  flat-bottomed 
platinum  dish  and  evaporate  to  dryness  on  a  water  bath.  Then  heat 
over  a  low  flame  (to  avoid  spattering)  until  the  contents  are  thor- 
oughly charred,  place  the  dish  in  an  electric  muffle,  preferably  with 
pyrometer  attached,  and  ignite  to  a  white  ash  at  a  temperature  not 
greater  than  500°  C.  (900°  F.).  Cool  and  weigh.  Express  the  re- 
sult as  grams  per  100  c.c.  Results  below  0.715  gram  per  100  c.c. 
indicate  added  water.  Multiply  by  the  factor  1.021  (dilution  of  the 
acetic  serum  being  2  per  cent)  to  obtain  the  result  on  the  sour 
serum  ash. 

SOUR  SERUM.— TENTATIVE 

"(a)  Zeiss  immersion  refractometer  reading. — Allow  the  milk 
to  sour  spontaneously,  filter  and  determine  the  immersion  refrac- 
tometer reading  of  the  clear  serum  at  20°  C-  A  reading  below  38.3 
indicates  added  water. 

(b)  Ash. — Determine  the  ash  in  25  c.c.  of  the  serum,  ob- 
tained in  (a),  as  directed  in  (b).  Results  below  0.730  gram  per 
100  c.c.  indicate  added  water. 


Journal  of  the  Asso.  of  Official  Agr.  Chemists,  Vol  II.,  No.  8,  Nov.  15,  1916. 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES         301 

ZEISS  REFRACTOMETER  READING  OF  COPPER  SERUM. 
TENTATIVE 

"To  one  volume  of  copper-sulphate  solution  (72.5  grams  of  cop- 
per sulphate  per  liter,  adjusted  if  necessary  to  read  36  at  20°  C.  on 
.the  scale  of  the  Zeiss  immersion  refractometer,  or,  to  a  specific  grav- 
ity of  1.0443  at  2°4°  —  )  add  four  volumes  of  milk.  Shake  well  and 
filter.  Determine  the  Zeiss  refractometer  reading  of  the  clear  serum 
at  20°  C.  A  reading  below  36  indicates  added  water. 

(In  conjunction  with  the  copper,  acetic  or  sour  serum  refraction 
method,  the  determination  of  the  ash  of  the  sour  serum  or  of  the 
acetic  serum  should  be  made  in  all  cases  where  the  indices  of  re- 
fraction fall  below  the  minimum  limit  so  as  to  eliminate  all  possi- 
bility of  abnormal  milk.)" 

DETECTION  OF  ARTIFICIAL  COLORING  * 
Leach's  Method 

"Warm  about  150  c.c.  of  milk  in  a  casserole  over  the  flame  and 
add  about  5  c.c.  of  acetic  acid,  after  which  slowly  continue  the 
heating  nearly  to  the  boiling  point  while  stirring.  Gather  the  curd, 
when  possible,  into  one  mass  by  the  stirring  rod,  and  pour  off  the 
whey.  If  the  curd  breaks  up  into  small  flakes  separate  from  the 
whey  by  straining  through  a  sieve  or  colander.  Press  the  curd  free 
from  adhering  liquid,  transfer  to  a  small  flask,  and  macerate  for 
several  hours  (preferably  over  night)  in  about  50  c.c.  of  ether,  the 
flask  being  tightly  corked  and  shaken  at  intervals. 

1.  "DETECTION  OF  ANNATO  (IN  THE  ETHER  EXTRACT) 

"Decant  the  ether  extract  as  obtained  above  into  an  evaporating 
dish,  place  on  the  water  bath,  and  evaporate  the  ether.  Make  the 
fatty  residue  alkaline  with  sodium  hydroxid,  and  pour  upon  a  very 
small  wet  filter  while  still  warm.  After  the  solution  has  passed 
through,  wash  the  fat  from  the  filter  with  a  stream  of  water  and 
dry  the  paper.  If,  after  drying,  the  paper  is  colored  orange,  the 
presence  of  annatto  is  indicated.  Confirm  by  applying  a  drop  of 
stannous  chlorid  solution,  which,  in  presence  of  annatto,  produces 
a  characteristic  pink  on  the  orange-colored  paper. 

1  United   States  Department   of  Agriculture,    Bureau   of  Chemistry,   Bulletin 
No.   107. 


302          DETECTION  OF  ADUI/TERANTS  AND  PRESERVATIVES 

2.    "DETECTION  OF  ANILIN  ORANGE   (IN  THE  CURD) 

"The  curd  of  an  uncolored  milk  is  perfectly  white  after  com- 
plete extraction  with  ether,  as  is  also  that  of  a  milk  colored  with 
annatto. 

"If  the  extracted  fat-free  curd  is  distinctly  dyed  an  orange  or 
yellowish  color,  anilin  orange  is  indicated.  To  confirm  the  presence 
of  this  color,  treat  a  lump  of  the  fat-free  curd  in  a  test  tube  with 
a  little  strong  hydrochloric  acid.  If  the  curd  immediately  turns  pink, 
the  presence  of  anilin  orange  is  assured. 

3.    "DETECTION   OF  CARAMEL    (IN  THE   CURD) 

"If  the  fat-free  curd  is  colored  a  dull  brown,  caramel  is  to  be 
suspected.  Shake  a  lump  of  the  curd,  as  in  (2),  with  strong  hydro- 
chloric acid  in  a  test  tube  and  heat  gently.  In  the  presence  of  cara- 
mel the  acid  solution  will  gradually  turn  a  deep  blue,  as  will  also 
the  white,  fat-free  curd  of  an  uncolored  milk,  while  the  curd  itself 
does  not  change  color-  It  is  only  when  this  blue  coloration  of  the 
acid  occurs  in  connection  with  a  brown  colored  curd,  which  itself 
does  not  change  color,  that  caramel  is  to  be  suspected,  as  distin- 
guished from  the  pink  coloration  produced  at  once  under  similar 
conditions  by  anilin  orange." 

4.    "LYTHGOE'S  TEST  FOR  ANILIN  ORANGE 

"Treat  about  10  c.c.  of  the  milk  with  an  equal  volume  of  hydro- 
chloric acid  (sp.  gr.  1.20)  in  a  porcelain  casserole  and  give  the  dish 
a  slight  rotary-motion.  If  an  appreciable  amount  of  anilin  orange 
is  present,  a  pink  color  will  at  once  be  imparted  to  the  curd  particles 
as  they  separate." 

Detection  of  Sucrose  in  Milk  to  Which  Sucrate  of  Lime1  (Visco- 
gen)  Has  Been  Added 

25  c.c.  of  milk  or  cream  are  shaken  in  a  small  Erlenmeyer  flask 
with  10  c.c.  of  a  5  per  cent  solution  of  uranium  acetate,  allowed  to 
stand  for  five  minutes  and  filtered  through  a  folded  filter.  If  the 
filtrate  is  not  clear,  pour  through  filter  again  until  clear.  To  10  c.c. 
of  the  filtrate  2  c.c-  of  a  cold  saturated  solution  of  ammonium 
molybdate  and  8  c.c.  of  hydrochloric  acid  (one  part  of  25  per  cent 
acid  to  seven  parts  of  water)  are  added.  The  mixture  is  shaken 

1  Barthel,  Milk  and  Dairy  Products. 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES          303 

and  placed  in  a  water  bath  at  80  degrees  C.  for  five  minutes.  In  the 
case  of  the  presence  of  sucrose  the  solution  becomes  more  or  less 
blue  according  to  amount  of  sucrose  present.  Upon  standing  in  the 
water  bath  for  a  longer  time  the  blue  color  becomes  deeper.  At  the 
end  of  ten  minutes  it  is  deep  blue,  while  in  the  absence  of  sucrose  at 
the  end  of  five  minutes  the  color  is  faintly  green,  which  deepens, 
but  never  acquires  a  blue  shade.  By  means  of  this  method  as  little 
as  .05  per  cent  sucrose  can  be  detected. 

Detection  of  Lime  in  Milk1 

Shake  250  c.c.  of  milk  at  15  degrees  C.  with  10  c.c.  of  a  10  per 
cent  solution  of  hydrochloric  acid.  Let  stand  at  room  temperature 
for  half  an  hour-  Filter,  returning  the  first  portion  of  filtrate  to 
the  filter.  Cover  filter  to  prevent  evaporation. 

Pour  104  c.c.  of  the  filtrate  (equal  to  100  c.c.  of  milk)  into  a 
200  c.c.  flask,  add  10  c.c.  of  a  10  per  cent  solution  of  ammonia  and 
fill  the  flask  to  the  mark  with  water  at  15  degrees  C.  Let  stand  for 
thirty  minutes.  Filter  through  folded  filter,  pouring  back  on  the 
filter  the  first  portion  of  the  filtrate.  Test  100  c.c.  of  filtrate  (equiv- 
alent to  50  c.c.  of  milk)  with  10  c-c.  of  5  per  cent  ammonium 
oxalate  solution  and  proceed  with  the  determination  of  the  lime  in 
the  usual  way,  but  without  warming  the  liquid. 

According  to  Baier  and  Neumann  and  corroborated  by  Luhrig, 
in  normal  milk  the  lime  in  the  serum  is  present  to  the  extent  of 
thirteen  to  eighteen  milligrams  per  100  c.c.  In  milk  to  which 
sucrate  of  lime  has  been  added  the  results  are  correspondingly 
higher. 

Detection  of  Gelatin2 

"Prepare  an  acid  solution  of  mercuric  nitrate  by  dissolving  mer- 
cury in  twice  its  weight  of  nitric  acid  of  1.42  specific  gravity,  and 
diluting  this  solution  to  twenty-five  times  its  bulk  with  water.  To 
10  c.c.  of  the  milk  or  cream  to  be  examined,  add  an  equal  volume 
of  the  acid  mercuric  nitrate  solution,  shake  the  mixture,  add  20  c.c. 
of  water,  shake  again,  allow  to  stand  five  minutes,  and  filter.  If 
much  gelatin  is  present  the  filtrate  will  be  opalescent  and  cannot  be 
obtained  quite  clear.  To  a  portion  of  the  filtrate  contained  in  a  test 


1  Barthel,  Milk  and  Dairy  Products. 

2  United   States  Department  of  Agriculture,    Bureau   of   Chemistry,   Bulletin 

107,   1912, 


304         DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES 

tube,  add  an  equal  volume  of  a  saturated  aqueous  solution  of  picric 
acid.  A  yellow  precipitate  will  be  produced  in  presence  of  any  con- 
siderable amount  of  gelatin,  while  smaller  amounts  will  be  indicated 
by  a  cloudiness.  In  the  absence  of  gelatin  the  filtrate  obtained  will 
remain  perfectly  clear." 

Detection  of  Preservatives 
CARBONATE  OR  BICARBONATE  OF  SODA*  (HILGER'S  METHOD) 

Dilute  50  c-c.  of  milk  with  250  c.c.  of  water.  Heat  and  precipi- 
tate with  a  small  quantity  of  alcohol.  Filter,  evaporate  the  filtrate 
to  one-half  its  original  volume  and  test  with  litmus  for  an  alkaline 
carbonate. 

FORMALDEHYDE    (HEHNER'S  METHOD) 

Dilute  the  milk  with  an  equal  volume  of  water.  Fill  a  test  tube 
one-half  full.  Add  commercial  sulphuric  acid,  specific  gravity  1.82- 
1.84.  The  acid  should  be  allowed  to  flow  down  the  side  of  the  tube 
so  as  to  avoid  excessive  mixing  of  acid  and  milk.  If  formaldehyde 
is  present  a  violet  ring  forms  at  the  junction  of  milk  and  acid.  By 
this  test  the  presence  of  one  part  of  formaldehyde  in  two  hundred 
thousand  parts  of  milk  can  be  detected.  When  more  than  .05  per 
cent  formaldehyde  is  present  the  violet  color  does  not  appear. 

The  same  color  reaction  is  obtained  when  the  acid  is  added  to 
the  milk  in  the  Babcock  test. 

Farrington  and  Woll 2  recommend  the  following  method : 
Measure  5  c.c.  of  milk  in  a  white  porcelain  dish,  add  5  c.c.  of  water, 
and  10  c-c.  of  hydrochloric  acid  containing  a  trace  of  ferric  chloride 
(Fe2Cl6).  Heat  the  mixture.  If  formaldehyde  is  present  a  violet 
color  appears. 

BORIC  ACID  AND  BORATES3 

"Render  decidedly  alkaline  with  lime  water  about  25  grams  of 
the  sample  and  evaporate  to  dryness  on  a  water  bath.  Ignite  the 
residue  to  destroy  organic  matter.  Digest  with  about  15  c.c.  of 
water,  add  hydrochloric  acid,  drop  by  drop,  until  all  is  dissolved, 
and  add  1  c.c.  in  excess.  Moisten  a  piece  of  delicate  turmeric  paper 
with  the  solution ;  if  borax  or  boric  acid  is  present,  the  paper  on 


1  Barthel,   Milk  and  Dairy  Products. 

2  Farrington  &  Woll,  Testing  Milk  and  Its  Products. 

3  United   States  Department  of  Agriculture,   Bureau  of   Chemistry.   Bulletin 
107,  1912. 


DETECTION  OF  ADULTERANTS  AND  PRESERVATIVES          305 

drying  will  acquire  a  peculiar  red  color,  which  is  changed  by  am- 
monium hydroxid  to  a  dark  blue-green,  but  is  restored  by  acid. 

A  preliminary  test  may  be  made  by  immersing  a  strip  of  tur- 
meric paper  in  about  100  c.c.  of  liquid  foods,  to  which  about  7  c.c. 
of  concentrated  hydrochloric  acid  has  been  added.  Solid  and  pasty 
goods  may  be  heated  with  enough  water  to  make  them  thoroughly 
fluid,  hydrochloric  acid  added  in  about  the  proportion  of  1  to  13, 
and  tested  in  the  same  manner-" 

BENZOIC  ACID1 

"Add  5  c.c.  of  dilute  hydrochloric  acid  to  50  c.c.  of  the  milk 
in  a  flask  and  shake  to  curdle.  Then  add  150  c.c.  of  efher,  cork  the 
flask  and  shake  well.  Break  up  the  emulsion  which  forms  by  aid 
of  a  centrifuge,  or  if  the  latter  is  not  available  extract  the  curdled 
milk  by  gently  shaking  with  successive  portions  of  ether,  avoiding 
the  formation  of  an  emulsion.  Transfer  the  ether  extract  (evapo- 
rated to  small  volume  if  large  in  bulk)  to  a  separatory  funnel  and 
separate  the  benzoic  acid  from  the  fat  by  shaking  out  with  dilute 
ammonium  hydroxid,  which  takes  out  the  former  as  ammonium 
benzoate.  •  Evaporate  the  ammoniacal  solution  in  a  dish  over  the 
water  bath  till  all  free  ammonia  has  disappeared,  but  before  dryness 
is  reached,  add  a  few  drops  of  ferric  chlorid  reagent.  The  char- 
acteristic flesh-colored  precipitate  indicates  benzoic  acid.  Care 
should  be  taken  not  to  add  the  ferric  chlorid  until  all  the  ammonia 
has  been  driven  off,  otherwise  a  precipitate  of  ferric  hydrate  is 
formed." 

SALICYLIC  ACID 2 

Acidulate  20  c.c.  of  milk  with  sulphuric  acid  and  shake  with 
ether.  Evaporate  the  ether  solution  and  treat  the  residue  with  al- 
cohol and  a  little  iron-chloride  solution ;  a  deep  violet  color  indi- 
cates the  presence  of  salicylic  acid- 

HYDROGEN   PEROXIDE3 
(Wilkinson  and  Peters'  Method) 

Add  four  drops  of  an  alcoholic  solution  of  4  per  cent  benzidine 
(paradiamidophenyl)  and  2  drops  of  acetic  acid  to  10  c.c.  of  milk. 
If  hydrogen  peroxide  is  present  the  milk  assumes  a  blue  color. 
.005  grams  of  hydrogen  peroxide  in  100  c.c.  of  milk  can  be  detected 
by  this  method. 


1  United  States  Department  of  Agriculture,   Bureau   of   Chemistry,   Bulletin 
107,  1912. 

2  Farrington  &  Wbll,  Testing  Milk  and  Its  Products. 

3  Barthel,  Milk  and  Dairy  Products, 


306  BACTERIOLOGICAL  ANALYSES 

CHAPTER  XXXIV. 
BACTERIOLOGICAL  ANALYSES 

While  it  is  obviously  beyond  the  scope  and  purpose  of  this 
volume  to  discuss  in  detail  the  technique  of  bacteriological  analyses 
and  microscopic  preparations  of  the  milk  products  described  herein, 
it  is  deemed  advisable  to  offer  some  suggestions  that  may  serve  for 
guidance  of  those  who  are  not  familiar  with  bacterial  fermentations 
in  condensed  milk. 

Sampling. — Take  samples  of  all  products  contained  in  open 
receptacles,  §uch  as  fluid  milk,  plain  condensed  bulk  milk,  barreled 
sweetened  condensed  milk  and  milk  powder,  in  sterile,  cotton  plugged 
test  tubes,  or  in  small  sterile  glass-stoppered  bottles,  and  keep  them 
in  a  cool  place,  preferably  not  above  35  degrees  F.  until  ready  to  use. 
Keep  canned  condensed  milk  sealed  in  the  original  package  until 
ready  to  use.  If  already  open,  invert  a  petri  disli  or  a  beaker  over 
the  can  to  avoid  contamination  from  the  air. 

Dilution  for  Numerical  Counts. —  Make  dilutions  in  250  c.c. 
glass-stoppered  flasks.  Before  opening  sealed  cans,  thoroughly 
wipe  off  the  entire  top  with  a  sterile  piece  of  cheese  cloth  soaked 
in  a  saturated  solution  of  mercuric  bichloride  or  a  5  per  cent  solution 
of  carbolic  acid  and  flame  the  top  of  the  can.  Open  evaporated 
milk  cans  by  punching  a  hole  into  its  top,  large  enough  to  insert  the 
discharge  end  of  a  graduated  pipette.  Open  sweetened  condensed 
milk  cans  with  a  sterile  knife  or  a  sterile  can  opener. 

In  the  case  of  fluid  milk  and  evaporated  milk,  measure  with  a 
sterile  graduated  pipette  two  cubic  centimeters  of  the  product  and 
198  cubic  centimeters  of  sterile  water  into  the  250  c.c.  flask.  In  the 
case  of  plain  condensed  bulk  milk,  sweetened  condensed  milk  and 
milk  powder,  use  tared  flasks  holding  about  150  cubic  centimeters, 
weigh  into  them  two  grams  of  the  product  and  add  enough  sterile 
water  at  a  temperature  of  98  degrees  F.  to  make  up  100  cubic 
centimeters.  Use  a  sterile  spoon  or  spatula  to  transfer  the  product 
to  this  flask.  A  wide-mouth  flask  is  preferable. 

The  above  represents  the  first  dilution.  The  flask  should  be 
carefully  shaken  until  a  hemogeneous  mixture  is  obtained  and  the 
soluble  portions  have  been  completely  dissolved. 

From  this  first  dilution  further  dilutions  are  made  in  sterile 
water  in  glass-stoppered  flasks,  according  to  requirements.  The 


BACTERIOLOGICAL  ANALYSES  307 

dilutions  should  be  sufficient  to  limit  the  number  of  colonies  on  the 
plates  to  about  50  to  100  per  plate.  Whole  milk,  as  it  arrives  at 
the  factory,  usually  shows  from  100,000  to  1,000,000  bacteria  per 
c.c..  Evaporated  milk  should  be  practically  sterile  unless  the  can 
shows  signs  of  fermentation  in  which  case  the  number  of  bacteria 
present  will  depend  on  the  age  of  the  sample  can ;  dilutions  as  high 
as  1:1,000,000  are  recommended  in  such  cases-  Plain  condensed 
bulk  milk  when  fresh  contains  from  about  1,000  to  100,000  bacteria 
per  c.c.,  when  several  days  old  and  in  the  absence  of  refrigeration, 
its  germ  content  is  often  much  greater.  Sweetened  condensed 
milk  averages  from  about  500  to  500,000  bacteria  per  c.c.  The  bac- 
terial content  of  milk  powder  is  variable,  no  approximation  can  here 
be  offered. 

Plating. — For  plating  the  following  media  are  recommended: 
Media  for  Total  Counts  and  also  for  acidifiers 
4  grams  beef  extract 
10  grams  peptone 
30  grams  lactose    * 
4  grams  sodium  chloride 
12  grams  thread  agar 
1000  c.c.  distilled  water 

Acidity  0.1  per  cent. 

For  acidifiers  add  1  c.c.  of  sterile  litmus  solution  to  each  plate 
before  pouring  the  agar. 

Media  for  Liquefiers 
4  grams  beef  extract 
10  grams  peptone 
30  grams  lactose 

4  grams  sodium  chloride 
150  grams  gelatin 
1000  c.c-  distilled  water. 
Acidity  0.1  per  cent. 

Media  for  Yeasts  and  Molds 
4  grams  beef  extract 
10  grams  peptone 
12  grams  agar 
1000  grams  wrhey 


308  BACTERIOLOGICAL  ANALYSES 

Acidity  0.2  per  cent. 

Add  1  c.c.  of  sterile  one  per  cent  tartaric  acid  solution  to  each 
plate  before  pouring  the  medium  over  the  dilution. 

Incubation. — Incubate  agar,  litmus  agar  and  whey  agar  plates 
at  35  degrees  C.  (95  degrees  F.)  for  at  least  three  days  before 
making  counts.  Incubate  gelatin  plates  at  21  degrees  C.  (70  degrees 
F.)  for  four  to  five  days  before  making  counts. 

Making  Counts.— The  colonies  on  the  plates  are  counted  most 
conveniently  by  placing  the  plates  over  a  standard  counting  plate. 
In  the  absence  of  such  a  plate,  place  the  petri  dish  upside  down 
ori  a  dark  surface  and  draw,  with  a  blue  crayon,  radial  lines,  divid- 
ing the  field  into  segments.  For  plates  containing  not  to  exceed 
100  colonies  eight  to  sixteen  segments  are  sufficient  for  easy 
counting. 

Qualitative  Determinations.— Numerical  counts  on  the  four 
kinds  of  media  recommended  above  usually  furnish  a  fair  general 
idea  of  the  types  of  bacteria  present. 

For  the  detection  of  gas-producing  species,  nutrient  bouillon 
containing  three  per  cent  lactose  and  three  per  cent  sucrose,  re- 
spectively, in  fermentation  tubes,  or  nutrient  agar  containing  three 
per  cent  lactose  and  three  per  cent  sucrose,  respectively,  in  test 
tubes,  are  serviceable. 

Cans  of  sweetened  condensed  milk  that  show  gaseous  fermenta- 
tion (swell  heads)  are  usually  due  to  certain  species  of  yeast,  which 
thrive  best  in  media  containing  sucrose. 

Cans  of  evaporated  milk  that  show  gaseous  fermentation 
(swell  heads)  are  usually  caused  by  anaerobic  putrefactive  bac- 
teria, of  which  Pleclridium  foetidum  is  a  most  frequent  repre- 
sentative, see  "Blown  Evaporated  Milk,"  page  226.  This  type  of 
micro-organisms  requires  strictly  anaerobic  cultural  conditions.  Un- 
der limited  laboratory  facilities  the  anaerobic  conditions  are  best 
produced  by  the  use  of  oxygen-absorbing  chemicals,  such  as  pyro- 
gallol  to  which  potassium  hydroxide  is  added.  Use  dry  commercial 
pyrogallol  and  potassium  hydroxide  sticks,  in  proportion  of  1  gram 
pyrogallol  to  .7  gram  potassium  hydroxide,  dissolved  in  about  2  c.c. 
of  water- 
Place  50  grams  of  pyrogallol  into  the  bottom  part  of  a  large 
size  desiccator.  Have  the  rim  of  the  desiccator  and  the  correspond- 


BACTERIOLOGICAL  ANALYSES  309 

ing  rim  of  the  cover  covered  with  a  mixture  of  half  paraffine  and 
half  bee's  wax.  Pour  into  the  pyrogallol  in  the  desiccator  100  c.c 
of  water  and  then  throw  in  35  grams  of  potassium  hydroxide. 
Quickly  insert  culture  tubes,  or  plates,  and  close  the  desiccator 
with  the  cover,  turning  the  cover  so  as  to  secure  a  perfect  seal. 
Apply  three  permanent  screw  clamps. 

Anaerobic  germs  of  the  type  of  Plectridium  foetidum  grow  best 
in  freshly  sterilized  milk.  In  the  case  of  Plectridium  foetidum  the 
milk  first  curdles,  then  digests,  forming  a  clear  yellow  liquid.  The 
digestion  begins  at  the  surface  and  proceeds  downward.  These 
cultures  develop  a  most  penetrating  foul  odor,  resembling  that  of 
spoiled  eggs.1 

The  technique  and  methods  for  determining  the  bacteriological 
flora  with  reference  to  cultural  and  morphological  characteristics  of 
individual  species  of  microbes  present,  are  identical  to  those  used 
in  the  bacteriological  study  of  milk  and  other  similar  products,  and 
which  are  fully  described  in  standard  manuals  on  bacteriology. 


1  For  further  details  on  the  technique  of  Anaerobic  Cultures  see  Hunziker 
Review  of  Existing  Methods  for  Cultivating  Anaerobic  Bacteria.  Journal  of 
Applied  Microscopy  and  Laboratory  Methods,  Vol.  V,  Nos.  3,  4,  5,  6. 


310 


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CONDKNSKD    MlLK   AND    MilyK    POWDER 


INDEX 


Absolute  pressure    78 

Absolute  vacuum    78 

Accidents   in   operating  pan,   preven- 
tion of   86 

Acid  fermentation     222 

Acid  flux    102,  203,  217 

Acid  in  milk   209, 236 

Acid  tests    45 

Acknowledgments     14 

Actinomycoses  odorifora  212 

Adulterants     229 

detection  of    295 

Age    152,200,214 

Agitation 95,195 

Albumin    168, 199,  264 

Altitude    79-82 

Altitude  of  various  cities  in  U.  S 81 

Altitude,     relation     to     atmospheric 

pressure   79-82 

Ammonium  hydroxide    145,  232 

Analyses  of — 

evaporated  milk   171,276,288 

milk    261,287 

milk  powder    283,  291 

sweetened  condensed  milk 

166, 282, 291 

Anglo-Swiss  Condensed  Milk  Co 20 

Annatto,   detection   of 301 

Anilin  orange,  detection  of 302 

Annual  output  of  condensed  milk  in 

U.  S 25 

Artificial  coloring   301 

Artificial  fats 176,  178,  231,  232 

Ash    165, 171, 218, 262, 273, 282 

Atmospheric  pressure   78-82 

B 

Babcock  test 269, 274, 283 

Bacteria  and  other  fungi — 

Actinomycoses  odorifora  212 

Bacillus  dimorphobutyricus   209 

Bacillus  esterificans    209 

Bacillus  mesentericus    .209 

Bacillus  putrificus     209 

Bacillus  saccharobutyricus     209 

Bacterium  fluorescens     .' 212 

Bacterium  prodigiosum   212 

Cladosporium  butyri    212 

Oidium  lactis    ! 212 

Penicilium  glaucum    212 


Penicilium  roqueforti   212 

Plectridium  foetidum    ...209,226,308 

Plectridium  novum    209, 226 

Bacteriological  analyses   306 

Barometric  condenser    69 

Barometric  reading    at    different    al- 
titudes       80 

Barrels,  condensed  milk 97,  204 

Basis  of  buying  milk 41 

Beaume  hydrometer    

90, 107, 108, 109,  272, 277 

Beet   sugar    58 

Benzoic  acid,  detection  of 305 

Bicarbonate  of  soda 232,  304 

Bitter  curd  in  evaporated  milk.  .223,224 
Blow-down  valve,  or  vacuum  breaker 

68,    69 

Body,  or  vapor  belt 65 

Boiling  test    46 

Borden's  Condensed  Milk  Co 20 

Borden,  Gail    18,19,   20 

Boric  acid  and  borates,  detection  of. 304 

Box   shooks 150 

Brands    156 

Brown  evaporated  milk 122,  228 

Brown  sweetened  condensed  milk... 214 
Buflovak  rapid    circulation    evapora- 
tor  134 

Buflovak  vacuum   drum   drier 239 

Building   and   equipment 31 

By-Products  Recovery  Co 24 


Campbell  process   132 

Cane  sugar  57 

amount  of   60-192,197,200 

determination  of  275 

effect  on  color 214 

effect  on   digestibility 60,175,176 

effect  on   sugar   sediment. ..  .192,  197 

effect  on   thickening 61,199 

incomplete  solution  of 192 

mixing  of   61, 165 

preservative   properties    of.... 57,    61 

price  of   61,187,189 

quality  of 59,207 

solubility  of   165 

solution  of    192 

Caramel,  detection  of 302 

Carbonate  of  soda,  detection  of 304 

Care   of   milk  utensils 44,210 

Casein    164,168,264 


CONDENSED  MILK  AND  MILK  POWDER 


313 


Casinate  of  zinc 102,  204 

Catch-all,  or  milk  trap 73,    74 

Checking  work  of  sealers 148 

Classification  of  condensed  milk  de- 
fects     190 

Coal,  cost  of 187, 189 

Coating  on  jacket  and  coils 164,  202 

Coils  in  vacuum  pan 65,   66 

Colostrum,  effect  of 220 

Commercial  glucose    57, 231 

Composition  of — 

concentrated  milk 132 

condensed  buttermilk    144 

evaporated  milk    167 

fat  in  condensed  milk 168 

milk  powder  245 

plain  condensed  bulk  milk... 170 

sweetened  condensed   milk 163 

Concentrated   milk    132 

Concentration,    ratio    of 

87,  107, 131, 197, 220 

Concrete  floors    33 

Condensed  buttermilk    141 

Condensed  milk  factories 27 

drainage   of    34 

economic     arrangement     of     ma- 
chinery      39 

equipment,  list  of 37 

essentials  of  suitable  location  of..  28 

factory    sanitation 41 ,  49,  201 ,  209 

floor  plan  of  factory 32 

milk   supply    28,    41 

sanitary  arrangement   of   machin- 
ery     41,209 

sewage  disposal    31 

tin  shop   39 

transportation   facilities    30 

water  supply    29,  213 

Condensed  milk  industry  17 

Condensed  skim  milk   131,  184 

Condensed  whey,    primost,    myseost.145 

Condensery  regulations    43 

Condenser  discharge    83, 84,   85 

Condensers   69 

Barometric    69 

capacity  of   83 

care  of   73 

surface    69 

wet-vacuum   spray   71 

Condensing  evaporated  milk 106 

Condensing     plain     condensed     bulk 

milk    129 

Condensing      sweetened      condensed 

milk    62,    85 

Contaminated  machinery   41,49,207 

Contaminated  sugar    59,  208, 209 

Contamination  of  milk  in  factory 207 


Contamination  of  milk  on  farm 

42,43,201 

Continuous  concentrator    24,136 

Control  of  quality  of  fresh  milk 43 

Cooling    44,  52,  94, 1 14,  125, 140 

Cooling  evaporated  milk 114,  253 

Cooling  in  sterilizer 125 

Cooling  plain  condensed  milk. .  .131, 140 
Cooling  sweetened  condensed  milk — 

agitation     94-97, 195 

effect  on  sugar  crystallization. 91, 195 

equipment    for     94-97 

method  of  94-97 

temperature    94-97 

Cost  of  manufacture 186-189 

Cream  of  tartar 232 

Curdy  evaporated  milk,  caused  by — 

acid  flux  in  cans 217 

concentration     108, 181,  216 

fractional  curdling   126,  217 

fractional  sterilization    126 

homogenizing    110,  221 

quality  of  fresh  milk 42, 104,  216 

sterilizing  heat    121,  122 

shaking    126-128 

Curdy  plain  condensed  bulk  milk: 
effect  of  quality  of  fresh  milk... 

42,43,129,215 

neutralizing  the  acid 215 


Decomposition  of — 

lactose  205 

sucrose  206 

Defective  cans  223,  224 

Defective  evaporated  milk  215 

Defective  milk  powder 246 

Defective  sweetened  condensed  milk.  191 

Dehydrated  milk 234 

Desiccated  milk 234 

Detection  of  beet  sugar 59 

Difficulties  in  meeting  evaporated 

milk  standards  181,217 

Digestibility  of  condensed  milk. .  172-178 

Digestion  experiments  172-175 

Dilution  of  condensed  milk 175 

Distribution  of  factories  in  U.  S 27 

Distribution  of  heat  in  sterilizer 121 

Dome  68 

Drainage  34 

Drawing  off  condensed  milk 94 

Drips  from  jacket  and  coils 67 

Dried  buttermilk  248 

Dried  whey  249 

Duration  of  sterilizing  processs 

122,221,226 

Dry  milk  234 

Dry- vacuum  pump  .75 


314 


CONDENSED  MILK  AND  MILK  POWDER 


Economic  arrangement  of  machinery  39 

Effect  of  heat  on  ash  of  milk 170 

Efficiency  of  shakers 128 

Efficiency  of  vacuum  pump 75 

Ekenberg  process 237 

Enzymes  in  condensed  milk 175 

Equipment  of  condensery 37,  38,  39 

Evaporated  cream    • 24 

Evaporated  milk  103, 149, 152, 157, 158, 

168,181,215,253,276,289 

Evaporated   milk   standards 181 

Evaporation,  affected  by — 

ratio  of  steam  and  water 82-86 

steam     pressure     in     jacket     and 

coils    82-86 

temperature     of     condenser     dis- 
charge  82-86 

temperature  in  pan 82-86 

vacuum  in  pan 82-86 

water   in  condenser 82-86 

Excessive  chilling  in  pan 193 

Excessive  stirring  of  sweetened  con- 
densed milk   94,  97,  195 

Exports  of  condensed  milk 161,  162 


Factory  plan    32,    35 

Factory   sanitation    41,49,201,207 

Fat  globules,  size  of 110,218,219 

Fat  in  condensed  milk.  .163, 169,  218, 

230, 231, 274,  281, 283,  288, 291 

Fat  in  milk  powder 245,  247,  283, 291 

Fat  in  malted  milk 252,  253,  291 

Feed  for  dairy  cows 43,  199 

Fermented  evaporated  milk 149,  222 

Fermented       sweetened       condensed 

milk   204 

Fermentation  tests  48 

Filling— 

in  barrels    97 

in  cans     ....97,116 

Filling  machines  97, 116 

Finishing  the  batch  (see  striking) 

Flux   for  soldering 102,203 

Food  value  of  condensed  milk.  .172-178 

Forewarmers,  heat  in 55,  57 

Formaldehyde,  detection  of 304 

Fractional  sterilization   126 


Gas  generators    103 

Gasoline  188,189 

Gas  supply   102 

Gebee   seal    98,99 


Gelatin,  detection  of 303 

Glucose 58,231 

Grainy  evaporated  milk 217 

Gritty    plain    condensed    bulk    milk, 
caused  by — 

crystallization  of  milk  sugar 

165,191,228 

degree    of    concentration 228 

Gunning  method  262 

H 

Health  of  cows 43 

Heating  the  fresh  milk.  .54,  105,  129, 139 

temperature     55,  105,  129,139 

Hebe  product    178,230,231 

Helvetia   Milk   Condensing  Company 

21,22,23,24 

History  and  development  of — 

condensed  milk  industry 17 

milk  powder   industry 234 

malted   milk  industry 250 

Homogenizers    110,  222 

Homogenizing — 

effect  on  curdiness    110, 221 

effect  on  fat    separation    110,221 

Horlick's  Malted  Milk  Co 250 

Horlick,  William 250 

How  to  keep  factory  in  sanitary  con- 
dition  41,49 

Hydrogen  peroxide,  detection  of.... 305 

I 

Imports  of  condensed  milk 161 

Improper  cooling   194 

Incomplete  solution  of  cane  sugar.. 

...... 61,165,192 

Incomplete   sterilization    224 

Incubation   128,  308 

Individual  standards   183 

Insoluble  albumin  169 

Inspection  of  cans 118, 148 

Interest  on  investment 189 

Invertase   206 


Jacket  in  vacuum  pan 64 


Labeling  149 

Labeling  machines   149 

Labels- 
cost  of   188, 189 

quality  of   150 

rust  spots  and  wrinkles 150 


CONDENSKD   MlUC   AND   MlI,K    POWDER 


315 


Labor,  cost  of 188, 189 

Lactase 206 

Lactose    (see  milk  sugar) 

Latzer,  Louis  23 

Leach's   method,   detection   of   color- 
ing    301 

Leaky  cans,  disposition  of 148 

Lime,  detection  of 303 

Loading  the  sterilizer 121 

Low's  volumetric  method 266 

Lumpy   sweetened   condensed   milk.. 201 
caused  by — 

acid  flux  in  tin  cans 102,  203 

contaminated  barrels    97,  205 

milk  from  fresh  cows 42,  203 

poor  quality  of  fresh  milk. ..  .43,  201 
unclean    factory  conditions. 41,  49,  201 

unclean  tin  cans 204 

white  and  yellow  buttons 201 


M 


McDonald  seal    98,99 

Malted  milk  250,251,252 

Market  prices    . .' 156 

Markets  of  condensed  milk 155 

Marking  the  cases 151 

Meyenberg,  John  B 22 

Milk,  care  of  before  manufacture. ...   51 

Milk,  quality  of 42,  49, 

....   104, 129, 201, 203,  206, 209,  216, 217 

Control  of  quality 43 

Milkers  and  milking 44 

Milk  of  lime 142,216,232 

Milk  powder   234 

analysis  of    245,282,291 

Buflovak  process 239 

Campbell  process   132 

composition     245 

Ekenberg  process   237 

history    and    development    of    in- 
dustry     234 

Just-Hatmaker  process 236 

markets    247 

Merrell-Gere  process 241 

miscibility    246 

packing  for  market 245 

quality  of  fresh  milk 236 

rancidity    247 

solubility 246 

water  content 246 

Wimmer  process 236 

Milk  strainers    44,  210 

Milk  sugar,  lactose — 

caramelizing  action    164, 170 

color    170,214,229 


crystallization    165, 193-199, 228 

determination    265,  274,  281 

powdered    to    control    crystalliza- 
tion   in    sweetened    condensed 

milk  198 

solubility    164,  191 

Milk  supply  28,41 

Milk  tests  for  purity — 

acid  tests   45 

boiling  test  46 

sediment  test  47 

sense  of  smell  and  taste 44 

temperature  test   44 

Milk  trap 73 

Mojonnier  test  for  fat  and  solids. 283-294 


N 


Nestle,  Henry    21 

Neutralizes    142,  232 

Neutralizing 215 

New  York  Condensed  Milk  Co 20 

Nitrogen,   total    262 

Nutritive    ratio    in    sweetened    con- 
densed milk   .  ..176 


Old  cans  on  the  farm 210 

Output  of  condensed  milk  in  U.  S. . .  25 


Packing    150 

Packing  for  export 151 

Page,  Charles  H 20 

Page,  David  21 

Page,  George  H 20, 21 

Page,  William  B 21 

Peroxide  of  hydrogen,  detection  of.. 305 

Pipe  covering    40 

Plain  condensed  bulk  milk. .  .19, 129,215 

Polluted  water 29, 213 

Practical   methods  of  systematic  ex- 
amination of  condensed  milk  for 

marketable  properties   258 

Preface    7 

Preface  to  Second  Edition 8 

Premiums,  cost  of 188 

Preservatives,  detection  of 304 

Pressure,  atmospheric  77-82 

in  homogenizer    ..113 

steam    82-84,200 

Primost    145 

Proteids     164, 168, 169, 262,  274, 282 

Putrid  sweetened  condensed  milk.153,  213 


316 


MlLK   AND    MlI^K    POWDER 


Quality  of   fresh  milk 

42. 43,  104, 105, 206,  209, 218,  236 

sugar    59,  207,  208,  210 

Quevenne  lactometer  261,  297 


Rancid  sweetened  condensed  milk,  af- 
fected by- 
bacteria  yeast,  molds 212 

polluted  water  213 

tropical  climates   213 

Rapidity  of  cooling  in  sterilizer 125 

Relation  of  steam  pressure  to  boiling 

point   77 

Roese-Gottlieb  method.  .270,  277,  282,  283 
Rust  spots  on  labels 150, 155 


Salicylic  acid,  detection  of 305 

Sampling  of  batch 93 

Samplers 93 

Sandy    sweetened    condensed     milk, 
caused  by — 

cane  sugar  content 192 

chilling  in  pan 193 

cooling,  improper   94, 194 

incomplete  solution  of  cane  sugar 

61, 165, 192 

stirring,  excessive    94,195 

Superheating  in  pan 87, 193 

warming   up    too    cool    condensed 

milk   195 

Sanitary  can    98,  99 

Sanitary  purity  of  condensed  milk..  172 

Sealing  cans    99,118,203,217 

Sealing  machines   100, 118 

Sediment  test 47 

Selling  expense  188,  189 

Separation  of  fat  in  evaporated  milk, 

affected  by   218 

concentration    220 

fat  globules,  size  of 168,218,219 

homogenizing    1 10,  221 

locality  218 

period  of  lactation 218 

season    218 

sterilizing   process    120-125,  220 

superheating  in  pan 106,  221 

turning  cans  in  storage 221 

Settled  sweetened  condensed  milk...  196 

affected  by — 
cane  sugar  content 60, 197 


density  of  condensed  milk 197 

fat  content   197 

turning  cans  in  storage 197 

Sewage  disposal   31 

Shakers    128 

Shaking    126 

Skimming,  detection  of 295,  301 

Solder    99, 101, 118, 187, 189 

Solids  in — 

evaporated  milk    

167, 180, 184,  277- 

milk    

milk  powder 

sweetened  condensed  milk... 

163,179,273, 

Solids  not  fat 

Specific    gravity.. 91, 107,  165,  170 


281,290 
262,  288 
282, 291 


290,297 

253, 297 

,261, 

272, 276 

.44,209 

....253 

115,253 


Stables    

Standardizing  

Standardizing  vat 52, 

Standards  of — 

condensed   skim   milk 184,  310 

evaporated  milk   180,  310 

malted  milk   252 

milk  powder  250 

sweetened  condensed  milk. .  .179,  310 

individual    183 

by  states    310 

Starch  in  condensed  milk 233 

Starting  the  pan 85 

Steam  necessary  for  evaporation....   85 

Sterilizers    120 

Sterilizing — 

distribution  of  heat 121 

duration  122,  216, 220 

temperature    122, 216 

Storage — 

advisability  of   154,  200 

duration     152,  200,  214 

purpose  152 

temperature  153,211,226 

turning  cans  in 197,  221 

Straining   44,  209 

Strainers    94,  193 

Striking  or  finishing — 

evaporated  milk   107 

plain  condensed  bulk  milk 131 

sweetened  condensed  milk 87 

Sucrate  of  lime,  detection  of 302 

Sucrose    (see  cane  sugar) 

Sugar  chute  61, 107 

Superheating    106, 130,  140 

Swelled  cans  due  to — 

chemical  action   227 

low  temperature  153,211,226 


CONDENSED  MILK  AND  MILK  POWDER 


317 


Sweetened  condensed  milk — 

adulterations    229-233 

bacteriological  analyses 306-309 

chemical  composition 162-166 

chemical  tests  and  analyses ...  260-283 

cost  of  manufacture 189 

dietetic  value   172-176 

defects 190-215 

examination    258 

federal  standards   179 

for  baby  food 175 

inspection  of  cans 147 

invention    18-20 

manufacture    54-103 

markets    155-160 

Mojonnier  test  288-290 

standards  by  states 310,  311 

standardizing   253 

storage    152,155 


Tests  and  analyses  of  milk,  condensed 

milk,  and  milk  powder 261 

Thermometer  in  vacuum  pan. .......  68 

Tin  cans,  cost  of 187, 189 

Tin  shop   39 

Total  cost  per  case 189 

Transportation  30, 188,  189 


Vacuo,  science  and  practice  of  evap- 
oration in   76-85 

Vacuum  pan  62 

Vacuum  pump   75 

Venthole  cans    117 

Venthole  fillers   117 

Ventilation    33 

w 

Warming  up  too  cold  sweetened  con- 
densed milk   195 

Water- 
in  milk    295 

in  condenser    82 

in  evaporated  milk 167 

in  sweetened   condensed   milk....  163 

supply    29 

Westphal  balance   261 

Wet-vacuum  spray  condenser 71 

Wildi,  John    23 


Yeast    206,207,308 


318  CONDENSED  MILK  AND  MILK  POWDER 


INDEX   TO   ADVERTISERS 


Page 

Alois  Aufrichtig  Copper  and  Sheet  Iron  Works,  St.  Louis,  Mo.  319 

A.  H.  Barber  Creamery  Supply  Co.,  Chicago. 319 

Bausch  and  Lomb  Optical  Co.,  Rochester,  N.  Y 320 

Buffalo  Foundry  &  Machine  Co.,  Buffalo,  N.  Y 321 

By-Products  Recovery  Co.,  Toledo,  0 322 

Creamery  Package  Manufacturing  Co.,  Chicago 323 

Davis-Watkins  Dairymen's  Mfg.  Co.,  Chicago 324,  325,  326 

F.  G.  Dickerson  Co.,  Chicago 327 

The  Engineering  Co.,  Fort  Wayne,  Ind 328 

J.  B.  Ford  Co.,  Wyandotte,  Mich 329 

General  Laboratories,  Madison,  Wis 330 

Geuder,  Paeschke  &  Frey  Co.,  Milwaukee,  Wis 331 

Groen  Manufacturing  Co.,  Chicago 332 

Hamilton  Brass  &  Copper  Works,  Hamilton,  0 320 

Arthur  Harris  &  Co.,  Chicago 334,  335 

Jalco  Motor  Co.,  Union  City,  Ind 333 

Jensen  Creamery  Machinery  Co.,  Long  Island  City,  N.  Y 336 

Mojonnier  Bros.  Co.,  Chicago 337 

Louis  F.  Nafis,  Inc.,  Chicago 338 

The  Pfaudler  Co.,  Rochester,  N.  Y 339 

Rice  &  Adams,  Buffalo,  N.  Y 342 

C.  E.  Rogers,  Detroit,  Mich 340,  341 

E.  H.  Sargent  &  Co.,  Chicago 342 

Schaef er  Manufacturing  Co.,  Berlin,  Wis 344 

The  Sharpies  Separator  Co.,  West  Chester,  Pa 343 

The  Simpson  Doeller  Co.,  Baltimore,  Md 344 

L.  Sonneborn  Sons,  Inc.,  New  York 345 

Stevenson  Cold  Storage  Door  Co.,  Chester,  Pa 346 

Sturges  &  Burn  Mfg.  Co.,  Chicago 348 

C.  J.  Tagliabue  Manufacturing  €o.,  Brooklyn,  N.  Y 347 

Torsion  Balance  Co.,  New  York 348 

The  Vulcan  Detinning  Co.,  Sewaren,  N.  J 349 


CONDENSED  MILK  AND  MILK  POWDER 


319 


Efficiency  and  Economy 

ARE   COMBINED  IN  THE   NATIONALLY  KNOWN 
"AUFRICHTIG"    VACUUM    PAN 

Our  Standard  "6' 6""  Pan  will  condense  10,000 
pounds  of  milk  in  one  hour  with  two  coil  and  12,000 
pounds  with  three  coil  system. 

Investigate  the  economically  operated  Jacketed  Hot 
Wells. 

We  manufacture  complete  equipment  used  in  Milk 
Condensories  and  Dairies. 

Highest  grades  of  materials  and  best  of  workmanship 
is  put  into  our  equipment. 

Write  for  specifications  and  prices. 

ALOIS   AUFRICHTIG    COPPER   &   SHEET 
IRON  MFG.  CO. 

Third  and  Lombard  Streets  Saint  Louis,  Missouri 


f|  "TITAN-ALEXANDRA" 

POWER  SEPARATOR 

r~T'HE   capacity   of   T-A    Separators 
1     ranges  as  high  as   10,000  Ibs.  per 

hour. 

T-A  Separators  invariably  skim  down 
to  one  one-hundredth  of  one  per  cent 
butterfat  loss,  as  shown  by  the  double 
Bore  Babcock  Bottle. 

T-A  Separators  seldom  clog,  and  our  records 
show  the  operation  of  many  machines  at  full 
capacity  for  five  and  six  hours  without  stopping, 
wnere  the  skim  milk  showed  only  ,-/,,,  of 
1  %  butter  fat  in  a  sample  taken  at  the  end 
of  the  run. 

T-A  Separators  are  very  light  running  requir- 
ing a  minimum  amount  of  power.  For  instance, 
the  largest  size  machine  is  run  with  a  2-inch  belt. 

We  carry  a  stock  of  machines  and  parts  at  our  Chicago 
Warehouse  and  we  would  be  pleased  to  go  into  further  de- 
tail regarding  this  Separator  at  your  convenience. 

A.  H.  Barber  Creamery  Supply  Co. 

CHICAGO,   ILL. 


320 


CONDENSED  MILK  AND  MILK  POWDER 


Model  FFS8 


Microscopes 

Standards    of   Optical    and 
Mechanical  Efficiency 

Model  FFS8  is  especially  suitable  for  bac- 

•••••^•••"i  teriological  work.  Has 
coarse  and  fine  focusing  adjustments,  with 
adjustment  heads  on  side  of  arm;  two  iris 
diaphragms,  three  objectives  —  including  oil 
immersion  —  in  revolving  nosepiece;  two  eye- 
pieces and  an  Abbe  condenser  in  quick-acting 
screw  sub-stage.  Number  of  magnifications 
obtainable  ranges  from  50  to  1260.  Con- 
struction is  rugged,  and  black  crystal  finish 
on  arm  and  base  unusually  durable. 

Write  for  catalog  describing  this 
and  other  models. 

Bausch  &  Ipmb  Optical  @. 

NEW  YORK       WASHINGTON     SAN  FRANCISCO 

CHICAGO  ROCHESTER,  N.  Y.  LONDON 

Leading  American  Makers 
of  High  Grade  Optical  Products. 


Hamilton 
Copper 
Vacuum 
Pan 

FOR  CONDENSING  MILK 


WE  GUARANTEE  our  Pan  to  use  the  smallest 
amount  of  condensing  water  and  that  there  is  ab- 
solutely no  loss  of  milk  during  operation. 

Our  Pan  has  greater  cubic  contents  per  size  than 
other  pans. 

Insist  on  knowing  the  thickness  of  copper  and 
square  feet  heating  surface  when  you  buy  a  Pan. 

We  make  Vacuum  Pans  in  3-ft.,  4-ft.,  5-ft.,  6-ft. 
and  7-ft.  diameters  and  make  reasonably  prompt 
shipments. 

We  build  the  Pans  complete  with  Forewarmers 
and  supply  the  Pump  when  desired. 
WHITE  FOR  PRICES 

Hamilton  Copper  &  Brass  Works 

HAMILTON,  OHIO 

ESTABLISHED       1885 


CONDENSED  MIIVK  AND  MILK  POWDER  321 

"BUFLOVAK" 

Vacuum  Dryers 

For  producing  Milk  Powder  and 
drying  Milk  Products 


The  "Buflovak"  Vacuum  Drum  Dryer  is  the  ideal  apparatus 
for  converting  milk  into  powder  form.  The  milk  is  dried  at  an 
extremely  low  temperature,  without  the  slightest  danger  of  over- 
heating or  contamination,  which  accounts  for  its  solubility  when 
dried  in  the  "Buflovak"  Dryer. 

The  dryer  is  so  constructed  that  every  part  of  the  interior  is 
readily  accessible  and  can  be  easily  cleansed,  thus  making 
the  apparatus  perfectly  sanitary — a  distinctive  feature  of  the 
"Buflovak"  Dryer.  Dries  skim  milk,  buttermilk,  malted  milk, 
and  other  liquid  material  containing  solids. 

The  "Buflovak"  Vacuum  Shelf  Dryer  is  used  for  drying  casein 
and  similar  products  which  must  be  dried  in  pans  or  trays. 

The  "Buflovak"  line  also  includes  the  Rapid  Circulation  Evap- 
orator which  is  especially  adapted  for  evaporating  milk  and 
other  delicate  and  foamy  liquids. 

Catalog  showing  all  types  of  "Buflovak"  Dryers 
and  Evaporators  will  be  mailed  on  request. 


Buffalo  Foundry  &  Machine  Co. 

20  Winchester  Avenue 
BUFFALO,  N.  Y. 

NEW  YORK  OFFICE:  17  BATTERY  PLACE 


322 


CONDKNSED    MlLK   AND    MlI,K    POWDER 


The  By-Products  Recovery  Company 

1 09  Chamber  of  Commerce  Building  Toledo,     Ohio 

Milk  Products  Department 

Automatic  Concentrators  for  "  Evaporated  "  Milk, 

"  Preserved  "  Milk,  Dry  Milk,  and 

Sugar  of  Milk  Factories 

Whole  Milk,  Skim  Milk,  Buttermilk  and  Whey  Rapidly  and  Economically 

Reduced  to  High  Concentrates  without  the  aid  of  Vacuum 

Pumps,  Condensers,  Water  or  Expert  Labor 


It  is  More  Economical  It  is  Less  Complicated 

It  is  More  Simple  to  Operate 

No  Water  Requirements  Excepting  for  Cooling 

More  than  100  Machines  Now  in  Use 


FOR  PARTICULARS  WRITE 


The  By-Products  Recovery  Co.,    Toledo,  Ohio 


CONDENSED  MILK  AND  MILK  POWDER  323 


An  Ideal  Cooler  forJCondensecHMilk 

THE  Wizard  Pasteurizer  makes  an  ex-r 
cellent    cooler    for    Condensed    Milk, 
because  the  cooling  is  done  gradually 
so    that    the    sugar    in    the    milk    does    not 
crystallize. 

Owing  to  the  efficient  valve  control,  cooling 
can  be  started  with  tempered  water  and 
cooled  down  as  wanted.  The  coil  is  multi- 
ple-fed, which  means  that  within  a  few 
seconds  after  the  cooling  medium  is  turned 
on  it  has  reached  every  part  of  the  coil.  Thus  the 
cooling  is  uniform  in  every  part  of  the  vat- 

The  Wizard  is  an  ideal  machine  in  which  to  cool  Con- 
densed Milk  and  is  exceedingly  practical  and  econ- 
omical. 

More  information  about  the  Wizard  will  be  furnished  gladly 
if  you  will  write, 

THE  CREAMERY  PACKAGE  MFG.  COMPANY 

Sales  Branch  Offices: 

(Write  to.  one  nearest  you.) 

CHICAGO,   ILL.  NEW  YORK    CITY  SAN   FRANCISCO.    CAL. 

61-67  W.  Xinzie  Street  47  W.  34th  Street  699  Battery  Street 

KANSAS  CITY,  MO.  OMAHA,    NEB.  TOLEDO,   OHIO 

931  W.  Eigrhth  St.  113  S.  Tenth  Street  119  St.  Clair  Street 

MINNEAPOLIS,    MINN.       PHILADELPHIA,    FA.          WATERLOO,    IOWA 

318  Third  Street,  N.  1907  Market  Street  406  Sycamore 


324 


CONDENSED  MILK  AND  MILK  POWDER 


OHIO 


CLEVELAND 


TIGER 


MILK  CANS 

The  "Super-Tinned"  feature  of  D-W-D  Milk  Cans  is  of  utmost 
importance.  The  tin  is  properly  put  on.  None  of  it  is  skimped  or 
rubbed  off.  This  is  the  most  effective  way  to  prevent  rust.  You  will 
easily  recognize  D-W-D  Milk  Cans  by  the  "wavy"  or  "cloudy"  ap- 
pearance of  the  tin  which  covers  the  steel  from  which,  they  are  made. 

Double  seamless  neck  construction  is  a  distinctive  advantage.  In- 
stead of  joints  or  seams  at  the  neck  to  become  jammed  and  leaky,  as 
is  common  in  many  constructions,  we  make  the  breast  and  outside  neck 
section  of  one  piece  of  steel.  The  two  neck  sections  are  jammed  to- 
gether, and  slightly  spun  out,  thereby  practically  welding  them  into  a 
double-thick  neck. 

The  bottoms  and  bottom  hoops  are  riveted  to  the  sides.  This  in- 
sures against  breaking  the  solder  by  hard  usage  and  rough  handling. 
Every  precaution  is  taken  to  furnish  you  with  superior  milk  cans  at  a 
reasonable  price.  Be  sure  you  give  D-W-D  Milk  Cans  their  rightful 
consideration  when  you  place  your  next  order.  "Honest  value"  is  our 
motto. 

DAVIS-XV&TKINS  DAIRYMEN^  MFG.CO. 


Sales  Offices:  Jersey  City,  N.  J. 


North  Chicago,  111.,  Denver,  Colo. 


CONDENSED  MILK  AND  MILK  POWDER 


325 


Progress  Can  Washer 

The  Progress  Can  Washer  has  given  fine  service  in  many  plants  for 
several  years.  Practical  service  has  proven  it  efficient,  and  a  profitable 
investment.  It  will  do  your  can  washing  the  way  it  should  be  done. 
Investigate  it  now. 

The  size  picture  above  washes,  sterilizes  and  dries  500  cans  and 
500  covers  per  hour.  The  large  diameter  permits  a  long  can  track, 
sufficient  jets  and  sprays  and  a  large  drying  compartment. 

The  drip  from  the  cans  is  caught  underneath  the  track  so  that  the 
can  is  thoroughly  drained  before  passing  into  the  machine.  Can  and 
cover  are  first  rinsed  inside  and  out.  Then  they  are  passed  over  jets 
and  sprays  from  which  hot  soda  solution  is  forced  at  high  pressure. 
They  are  then  rinsed,  sterilized  and  dried.  It  is  a  continuous  auto- 
matic operation  which  does  the  work  right  and  at  low  operation 
expense. 

Write  our  nearest  office  about  your  can-washing  needs.  Our  line 
includes  many  sizes.  If  you  want  to  see  a  Progress  Can  Washer  in 
operation,  ask  us  for  the  name  and  address  of  the  nearest  plant  now 
so  equipped. 

DAMS-\\^TKINS  DAIRYMEN'S  MFG.GO. 


Sales  Offices:  Jersey  City,  N.  J. 


North  Chicago,  111.,  Denver,  Colo. 


326 


CONDENSED  MILK  AND  MILK  POWDKR 


Progress  Homogenizer 

Progress  Homogenizers  are  built  in  four  sizes.  Number  1  handles 
90  gallons  per  hour;  Number  2,  200  gallons;  Number  4,  400  gallons; 
Number  8,  800  gallons.  Each  machine  is  builded  full  rated  capacity, 
and  it  will  do  the  work  it  is  intended  for  at  small  expense  and  to 
excellent  advantage. 

This  machine  quickly  pays  its  cost,  and  oftimes  it  results  in  a 
saving  equal  to  many  times  its  cost  in  a  very  short  time.  You  manu- 
facturers of  evaporated  milk  must  avoid  the  waste  which  may  be  ocas- 
siorued  by  "separated"  milk.  The  Progress  Homogenizer  so  breaks 
up  the  fat  globules  that  the  cream  cannot  possibly  separate.  It  will 
not  injure  the  casein. 

Write  to  our  nearest  office  for  full  information  and  prices  on  the 
size  you  need.  Many  plants  have  several  of  these  machines.  Tell  us 
about  the  size  of  your  business  so  we  can  judge  as  to  your  require- 
ments. "The  Davis-Watkins  Line"  includes  everything  needed  in  the 
manufacture  of  Dairy  Products.  Let  us  quote  you  prices  and  co- 
operate with  you.  We  have  thousands  of  "Satisfied  Customers."  Why 
not  join  your  name  to  this  already  long  list?  We  want  your  business 
and  you  need  our  help. 

DAMSA^VTKINS  DAIRYMEN'S  MPG.Ca 


Sales  Offices:  Jersey  City,  N.  J. 


North  Chicago,  111.,  Denver,  Colo. 


CONDENSED  MILK  AND  MILK  POWDER 


327 


The  Dickerson  Vent  Filler 


OUR  ORIGINAL  IDEAS  ON  CANNING  MILK  HAVE 
NEVER  BEEN  IMPROVED  UPON. 


JT    S**  Baby  Size 

I  T    you  appreciate  sanitary  values,  economy  in  opera- 
-*  /      tion,  accuracy  in  filling  and  neatness  in  the  appear- 
^        ance  of  your  finished  product: — 

GET  IN  TOUCH  WITH  DICKERSON. 

The  F.  G.  Dickerson  Co. 

541-557  W.  Washington  Blvd.  CHICAGO 


328 


CONDENSED  MILK  AND  MILK  POWDER 


The  Engineering  Company 

Fort  Wayne,  Indiana 


We  build  Sterilizers  from  40  cases  per  charge  to  240  cases  per  charge  and  all 
intermediate  sizes.  The  latest  scientific  and  mechanical  ideas  are  embodied  in 
this  machine.  It  is  sanitary;  the  distribution  of  heat  is  absolute  and  under  full 
control  of  the  operator;  it  requires  less  operating  power,  water  and  steam  than 
any  other  style  of  sterilizer;  it  saves  time  in  loading  and  unloading,  cannot  be 
overbalanced,  has  no  exposed  gears  and  runs  silently.  Our  shakers  are  con- 
structed with  a  wide  range  of  capacity  and  are  giving  excellent  satisfaction. 

We  build  these  machines  with  clutch  and  pulley  for  driving  with  belt  or  with 
motor  directly  connected  by  means  of  silent  gears. 

I    THE  ENGINEERING  CO.    I 

Fort  Wayne,  Indiana 


CONDENSED  MILK  AND  MILK  POWDER 


329 


Factory  Sanitation 

From  a  beginning  many  years  ago  with  the  discovery 
of  the  relationship  between  cleanliness  and  health  on  up 
to  the  present  date  no  more  logical  reason  has  been  dis- 
covered why  it  is  profitable  to  use 


than  the  one  reason  "It  Cleans  Clean." 

However  necessary  it  is  to  avoid  impairing  the  health 
of  your  patrons,  the  commercial  advantage  of  turning  out 
a  pure,  wholesome  product  is  more  generally  the  end  sought 
in  maintaining  clean,  sweet,  sanitary  conditions  where  your 
product  is  manufactured. 

Just  how  to  keep  your  factory  and  equipment  in  this 
sanitary  condition  with  the  least  expenditure  of  time,  labor 
and  money  is  a  question  easily  answered  by  the  results  ob- 
tained from  the  use  of  Wyandotte  Dairyman's  Cleaner  and 
Cleanser. 

Your  supply  house  will  fill  your  order 
for  this  cleaner  on  a  guarantee  of  satis- 
faction, or  money  refunded. 

It  Cleans  Clean. 

in  every  package 

The  J.  B.  Ford  Co.,  Sole  Mnfrs  ,  Wyandotte,  Mich. 


330 


CONDENSED  MILK  AND  MII,K  POWDER 


Do  Not  Scrape  Piping 

Easy  to  Keep  Clean  and  Purified  when  B-K  is  used. 

The  use  of  Bacili-Kil  (B-K)  has  become  standard  practice  in  most  of  the 
important  milk  product  plants  thruout  the  United  States  and  Canada,  New 
Zealand  and  other  dairy  countries.  B-K  is  safe  to  use  anywhere — gives  posi- 
tive sterilization  in  places  where  steam  cannot  be  used.  Wherever  used,  B-K 
reduces  the  bacterial  count,  increases  the  flavor,  value  and  keeping  quality 
of  milk  and  all  dairy  products. 

NOTE  THESE  REMARKABLE  QUALITIES: 

POWERFUL:  By  Government  method  of  test,  B-K 
has  over  ten  times  greater  germ  killing  strength  than 
undiluted  carbolic  acid.  Much  stronger  than  coal  tar 
disinfectants — much  safer. 

SAFE:  B-K  contains  no  poison,  acids,  oils  nor  pre- 
servatives. 

CLEAN:      B-K     is     colorless  —  clear     and     clean     as 
water — leaves   no   stain   on   utensils,   floors   or   walls. 
DEODORANT:     B-K   destroys    foul   odors   by   killing 
the   bacteria   and   germs   of  decay   which   cause   them. 
Unlike  other  deodorants,   it  leaves  no  odor  of  itself. 
ALBUMIN"    SOLVENT:      B-K    dissolves     albuminous 
matter  such  as  the  milk  solids  which  collect  in  pip- 
ing, etc.     This  enables  the  B-K  disinfecting  solution 
to  reach  the  hidden  bacteria,  while  steam  and  scald- 
ing  water    harden   the   milk   solids,    leaving   them    to 
contaminate  future  runs. 
CHEAP   TO   USE:     B-K   is    so   much    stronger    than   other    disinfectants   that 
more  water  can  be  used.     It  goes  farther,   therefore  costs  less. 
B-K  gives  cheap  and   effective  sanitation   in  milk  and   dairy  products   plants 
by   sterilizing   cans,    vats,    piping,    pumps,    pasteurizers,    separators,    churns, — 
by  disinfecting  and  deodorizing  floors,   drains,   cold   storage   rooms,   etc. 

Bulletins  and  Complete  Information  Sent  on  Request. 
READ  THIS  LETTER 

General   Laboratories,  Nashville,   III., 

Madison,   Wisconsin.  June  18,  1916. 

We  have  been  constant  users  of  BK  for  several  years  and  I 
think  there  is  nothing  like  it  for  the  work  for  which  it  is  recom- 
mended. 

We  are  operating  a  condensed  milk  plant  and  would  say 
that  each  and  every  milk  pipe  line,  tank,  or  vat,  as  well  as  all 
milk  cans  have  their  daily  bath  in  a  solution  of  BK. 

ST.  LOUIS  DAIRY  COMPANY, 

(Signed)     A.  J.   Volkman,  Mgr. 

"THE  STANDARD  OF  COMPARISON" 


Separator  bowl  showing  how 

slime  falls  away  when 

B-K  is  used. 


NOT  A 
POISON 


LEAVES 
NO  ODOR 


Awarded  Gold 
Medal  Pan.-Pac. 

Exposition. 


CLEAN  —  POWERFUL  —  SAFE 

GENERAL  LABORATORIES: 
18  So.  Dickinson  St.,  Madison,  Wisconsin 


CONDENSED  MILK  AND  MILK  POWDER 


331 


SANITARY  M  UK  CANS 


WILL  SERVE  YOU  LONG  AND  WELL 


332  CONDENSED  MILK  AND  MILK  POWDER 

Groen  Mfg.  Co 

4535  -  37  Armitage  Avenue 
CHICAGO,  ILL. 

MANUFACTURERS      OF 

MILK  CONDENSING 
EQUIPMENT 


VACUUM  PANS 

WITH    VERTICAL    OR   HORIZONTAL    CONDENSERS 

Forewarmers  Storage  Tanks 

Can  Coolers  Pipe  Coolers 

Receiving  Tanks  Cooling  Coils,  Etc, 

Get    Our    Quotations 


CONDKNSED   MlLK   AND   MlLK    POWDER 


333 


MOHTOR  COMPANY 

UNION  cm:  INDIANA 


MOTOR  COMPANY 
UNION  Cm:  INDIANA 


JALCO  ELECTRIC 
TESTERS 


«4»  — "8"  —  "12"  — 


MOTOR  COMPANY 
UNION  Cm:  INDIANA 


Sold   by    all 

LEADING 
SUPPLY 
HOUSES 


MOTOR  COMPANY 
UNION  OT*  INDIANA 


334 


CONDENSED  MILK  AND  MILK  POWDER 


HARRIS  COPPER  VACUUM  PAN 

FOR  MILK  CONDENSING 

AWARDED  GOLD   MEDAL 
PANAMA-PACIFFC    INTERNATIONAL   EXPOSITION 


ARTHUR  HARRIS  &  Co. 

Pioneer  Constructors  of  Milk  Condensing  Apparatus 

21  2-21  S  CURTIS  ST.,  CHICAGO,    ILLINOIS 


CONDENSED  MILK  AND  MILK  POWDER  335 


Harris  Copper  Vacuum  Pans 


AND 


Milk  Condensing  Machinery 

Have  been  our  Specialty  for  over 
30  years.  Over  this  period  we  have 
continuously  produced  High 
Grade  Apparatus  which  has  given 
most  gratifying  results  both  in 
production  and  service.  Large 
capacity  Harris  Copper  Vacuum 
Pans  in  service  today  total  in  the 
hundreds. 

We  Solicit  Your  Inquiries  for 

VACUUM  PANS  STERILIZERS 

FOREWARMERS  SHAKERS 

VACUUM  PUMPS  LABELING  MACHINES 

COOLING  MACHINES  RUBBER  PACKED  COCKS 

PIPE  COOLERS  SAMPLERS 

RECEIVING  TANKS  SUPERHEATER  BULBS 

STORAGE  TANKS  COOLING  COILS 

FILLING  MACHINES  WEIGH  SCALE  TANKS 

PEEPHOLE  GLASSES,  ETC. 


Arthur  Harris  &  Go. 

Established     1884 

212  -  218  Curtis  St.  Chicago,  Illinois 


336  CONDENSED  MILK  AND  MILK  POWDER 


Jensen  Vertical  Coolers 


SPECIALLY  BUILT  FOR  COOLING 

CONDENSED  AND  EVAPORATED  MILK 

ELIMINATE  CRYSTALLIZATION. 

Furnish  Correct  Amount  of  Agitation  to  Produce  a  Smooth  Product. 

Eliminate  Air  and  Gases  Thru  Rotation  of  Double 

Helical  Coil  During  Cooling  Process. 

PREVENT  CONTAMINATION 

as  all  Packing  and  Stuffing  Boxes  are  Outside  and  Above  the  Machine. 

Ask  for  Catalog  No.  20 A. 

Jensen  Creamery  Machinery  Company 

Long  Island  City,  N.  Y.  Oakland,  California 

Southern    Distributor: 
BLANK E  MFG.  <$   SUPPLY  CO.,  St.  Louis,  Mo. 


CONDENSED  MILK  AND  MILK  POWDER  337 

It  PAYS  to  Standardize 
Your  Dairy  Products 

YOU  can  standardize  your  dairy  products  easily,  rapidly  and  accurately 
by  using  the  Mojonnier  Tester  for  Butter  Fat  and  Total  Solids  in 
Milk  or  Milk  Products.     You  can  standardize  the  Butter  Fat  to 
within  .03%   and  Total  Solids  to  within  .10%  of  any  standard,  and  tests 
can  be  made  in  a  half  hour. 


Finding  the  Butter  Fat  and  Total  Solids  contained  in  Dairy  Products. 

The  cash  value  of  standardizing  dairy  products  is  apparent  to  any  business  man. 
We  also  manufacture  and  sell  a  large  line  of  apparatus  for  standardizing  milk  and 
milk  products,  including 


Ice  Cream  Overrun  Tester. 
Fresh  Milk  Tester. 
Culture  Controller. 
Complete  Milk  Laboratory 
Equipment. 


Evaporated  Milk  ControlUr. 
Vacuum  Pan  and  "Striker." 
Storage  and  Mixing  Tanks. 
Complete  Equipment  for  Condensed  and 
Evaporated  Milk  Plants. 


Complete  information  gladly  furnished  on  any  of  this  apparatus. 


MILK    ENGINEERS 
833  W.  de^kson  Boul.  Chicag 

Eastern  Office:  501  Fifth  Avenue,  New  York. 


338 


CONDENSED  MILK  AND  MILK  POWDER 


Invest  Your  Money 

Where  It  Will  Bring  You 

The  Best  Returns 


A/TONEY  paid  for  NAFIS  SCIENTIFIC  GLASS- 
WARE  is  invested — not  merely  spent — be- 
cause Nafis  Glassware  is  guaranteed  to  be  Accurate 
and  to  give  excellent  service. 

It  is  used  by  the  most  efficient  Cream- 
eries, Cheese  Factories,  Condensing 
Plants,  Dairy  Schools 
and  Experiment  Sta- 
tions because  of  its 

Accuracy 

and 
Quality 


If  your  dealer 
cannot     supply 
j    you  with 

NAFIS 
GLASSWARE, 

write  for  our  illustrated  cata- 
logue and  list  of  our  distributors. 


Nafis 

Automatic 

Acidity 

and 

Salt  Testing 

Outfits. 


LOUIS  F.  NAFIS,  Inc 


MANUFACTURERS   OF   CREAMERY   GLASSWARE 

544  Washington  Blvd.  CHICAGO 


CONDENSED  MILK  AND  MILK  POWDER 


339 


'The  Most  Efficient  Arrangement 


Cold  Medal  Awarded  at 
Panama- Pacific  Inter- 
national Exposition, 
San  Francisco, 
1915. 


that  has  ever  been  suggested  to  me" 
commented  the  head  of  one  of  the 
largest  condensing  companies  upon  the 
PFAUDLER  GLASS  ENAMELED 
STEEL  Jacketed  Milk  Storage  Tanks 
which  he  has  used  for  a  number  of 
years. 

By  quickly  cooling  and  safely  storing 
the  fluid  milk,  they  balance  the  load 
on  your  vacuum  pans,  and  permit  one 
pan  to  work  a  full  day  and  do  the  work 
of  two  pans  at  a  half  day  each. 

These  Tanks  prevent  milk 
spoilage,  are  exceptionally 
easy  to  clean,  and  save  much 
in  labor  and  general  upkeep. 
Their  GLASS  linings  are 
fused  into  substantial  plate 
steel  bodies  and  are  very 
durable.  They  do  not  cor- 
rode nor  impart  metallic 
flavors  to  the  milk. 

We  also  build  Enameled 
Steel  Forewarmers,  Receiv- 
ing Tanks,  Weigh  Tanks, 
Plain  Storage  Tanks,  Truck 
Tanks,  etc. 

Jacketed  Cooling  and  Storage 
Tank,  built  either  in  one  piece 
or  in  sections;  equipped  either 
with  Mechanical  or  Air  Agi- 
tator. 


THE  PFAUDLER  CO.,    ROCHESTER,  N.  Y. 


Boston 
Detroit 
Pittsburgh 


Branch  Sales  Offices : 

New  York 

Chicago 


St.  Louis 

Minneapolis 

San  Francisco 


340  CONDENSED  MILK  AND  MILK  POWDER 

KB  -D* 

D  D 

Sterilizers 

IN  ALL  STANDARD  CAPACITIES 


STERILIZER 
LOADING    END 


Equal  Heat  Distribution 

Rapid  Loading  and  Unloading 

Entire  Load  Carried  on  Roller 

Bearings— Requiring  Minimum  Power 


Our  Shakers  are  also  good 


C.  E.  ROGERS 

34-42  Goldsmith  Ave.         Detroit,  Mich. 

D  D 


CONDENSED  MILK  AND  MILK  POWDER 


341 


High  Type  Copper 

Vacuum 
Pans 


Save  Fuel,  Water 
Milk,  Labor 

Largest 
Capacities 

Special  Coils 
for  utilizing 
Exhaust  Steam 

MANUFACTURED  COMPLETE  BY 

C.E.Rogers 

34-42  Goldsmith  Avenue 
Detroit,  Michigan 


342 


CONDENSED  MILK  AND  MILK  POWDER 


R  &  A  Hydraulic  Can  Washer,  Sterilizer 
and  Drier  for  Clean,  Dry  Sterile  Cans 

RICE  $  ADAMS,  Inc.,  166-182  Chandler  St.,  Buffalo 


Fig.  417     Two-Tank  Machine  Showing  Powerful  Blower  and  Hot  Air  Drier. 


SARGENT'S  ELECTRIC  DRYING  OVEN 

(PATENTED) 

May  be  set  for  any  tempera- 
ture from  70°  C.  to  150°  C. 
and  will  maintain  that  tem- 
perature indefinitely.  Almost 
a  necessity  in  Milk  Product 
Laboratories  where  the  main- 
tenance of  the  lowest  usable 
temperature  is  imperative. 

Price  complete  with  six- 
foot  cord,  plug  and  thermo- 
meter, $27.50.  Wound  for 
110  or  220  volt  current. 


Complete  catalogues  furnished  upon 
application. 


E.  H.  SARGENT  &  CO. 

Manufacturers.  Importers.  "Dealers  in   Chemicals  and  Chemical 
^/ipparatus  of  High  Grade  only. 

125-127  West  Lake  Street  CHICAGO 


CONDENSED  MILK  AND  MILK  POWDER 


343 


if: 

ill 

*! 


m 

*! 


Maintenance  Guarantee 


19 


for  llje  Consiberatwn  of  Twelve  Dollars  we  agree 

to  furnish' for  this  machine,  Serial  No ,  such 

repairs  and  oil  as  may  be  required  by  ordinary  use  for 
a  period  of  six  years  from  the  date  of  this  guarantee. 
All  requests  for  parts  or  oil  covered  by  this  guar- 
antee-must be  signed  by  owner  of  machine,  and  the 
old  parts  must  subsequently  be  returned,  transporta- 
tion prepaid,  to  us  for  credit. 

This  guarantee  is  made  in  good  faith  and  does  not 
cover  accidents  or  misuse.  It  is  our  policy  to  be  liber- 
al in  its  fulfillment.  We  are  dependent  upon  the  fair- 
ness of  the  owner  and  his  care  of  the 
machine  for  protection  against  loss. 

£t)f  -feharplcs  Separator  Co. 


District  Manager. 


$2 


oil  and 
repairs 


The  Sharpies  Maintenance  Guarantee  makes  it  positive 
that  your  oil  and  repair  costs  on  a  Sharpies  will  not 
cost  over  $2  a  year — and  holds  good  for  six  years.  Com- 
pare this  with  the  $40  to  $75  a  year  cost  for  repairs 
alone  on  disc  type  separators. 

SHARPIES— 

Factory  Separators  Super  Clarifiers 

Sharpies  cuts  excessive  upkeep  costs  by  eliminating  all 
trouble-giving  parts — no  tread  wheels  or  neck  bearings, 
no  discs  to  throw  bowl  out  of  balance,  no  steel  points 
under  spindle,  no  wear  on  spindle,  etc. 

Takes  only  25  to  30  Ibs.  of  steam  to  operate  Sharpies 
Separators — 10  to  15  Ibs.  for  the  Super  Glarifier — A  big 
saving  in  steam! 

Write  to  nearest  office  for  catalog — mention  the  type 
of  machine  you  need. 

The  Sharpies  Separator  Co. 

WEST  CHESTER,  PA. 

BRANCHES:  Chicago,  San  Francisco,  Toronto 


344  CONDENSED  MILK  AND  Miuc  POWDER 


Schaefer  Manufacturing  Go. 

BERLIN        Jt          H          6        WISCONSIN 
MANUFACTURERS       OF 

CONDENSED  and  EVAPORATED 

MILK  MACHINERY 


Sterilizers,  Shakers,  Test  Sterilizers,  Fillers,  Auto- 
matic  Machinery,    Can  Conveyors,  Testers, 
Can  Coolers  and  Special  Machinery    • 
for  Special   Purposes. 


CONDENSED  MILK  AND  MILK  POWDER  345 


White  sanitary  washable  interior  coating 

Cemcoat  is  a  snow-white  coating  applied  like  paint.  It 
is  washable.  The  Boston  Bio-chemical  Laboratory  after 
an  exhaustive  test  finds  that  Cemcoat  affords  no  ground 
for  accumulation  of  bacteria  and  fungi.  Heat  and  cold 
does  not  affect  Cemcoat — it  is  water-proof. 


TRADE    MARK 


Dust-proofs  and  wear-proofs  concrete 
floors  by  chemical  action 

Lactic  acid  in  milk  causes  deterioration  of  concrete  floors. 
Extreme  wear  develops  holes.  You  can  prevent  these 
conditions  by  treatment  with  Lapidolith,  which  is  a 
permanent  positive  cure. 

A  chemical  combination  is  effected  thru  the  action  of 
Lapidolith  on  the  cement  making  the  floor  granite-like 
and  non-absorbing  so  that  it  will  withstand  the  heavy 
wear  quite  common  in  milk  and  creamery  plants. 

Many  dairies  and  creameries,  after  thoroughly  testing 
these  materials  for  a  number  of  years  have  expressed 
complete  satisfaction.  We  will  gladly  refer  you  to  these 
satisfied  users, — send  you  samples  and  complete  informa- 
tion upon  request.  Write  to-day  to  Dept.  No.  50, 

L.  Sonneborn  Sons,  Inc. 

264  Pearl  Street  NEW  YORK 


346 


CONDENSED  MILK  AND  MILK  POWDER 


Doors 

Doors  are  just  a  big  valve  and  are  a  weak  point  in  all  Cold  Storage.  Their  insulation 
is  important,  so  is  their  tightness,  but  their  quickness  is  vastly  more  so,  because  it 
affords  the  workman  less  excuse  for  leaving  them  open. 

Stevenson's  latest,  the  "Door  that 
cannot  stand  open."  Cuts  off  all  rush 
of  air,  ends  all  losses  from  operating 
and  neglect  of  any  cold  storage  door. 
Made  with  port  for  overhead  track  or 
without.  The  ideal  freezer  door.  Rids 
itself  of  ice..  Doors  lift  a  little  as 
they  open,  hence  confectioners  and 
others  moving  liquids  in  wheeled 
tanks,  can  have  a  perfectly  level 
floor.  No  frail  spring  hinge  nuisance 
to  renew  every  little  while,  put  off 
each  time  till  the  entire  price  of  this 
door  is  wasted. 

All  Stevenson  Doors  have  been  de- 
veloped with  these  features  constantly 
in  mind.  The  Doorframe  is  adjustable 
to  conform  always  to  the  Door  thus 
insuring  perfect  fit  and  freedom,  with- 
out expense  or  refitting.  The  thick 
portion  of  the  Door  fits  loosely  in  the 
frame  and  thus  avoids  binding. 

The  overlapping  margin  of  the  Door 
is  held  tightly  to  its  seat  against  the 
face  of  the  Doorframe  by  powerful 
elastic  hinges  having  the  largest  bear- 
ings made  for  Doors  of  such  weight. 
Its  Self-Acting  Roller  Fastener  has 
enormous  strength,  is  arranged  for 
padlock— no  slackening  as  it  latches — 
the  soft  hemp  gasket  in  the  joint  is 
always  in  sight.  A  mere  touch  frees 
and  opens  it  from  either  side. 

Stevenson  Doors  swing  entirely  out 
of  the  passageway,  when  opened,  hence 
the  Doorway  may  be  6  inches  nar- 
rower, an  important  economy  in  re- 
frigeration. The  jambs  of  the  Door- 
frames are  straight,  clean,  sanitary. 
No  frail  rebate  strips  in  the  Doorway. 

The  opening  in  wall  as  constructed 
in  this  year  1918,  should  be  3  %  inches 
wider  and  4%  inches  higher  than  the 
clear  size  of  our  Doorway.  Follow 
construction  numbered  1  and  2. 

Fig.  B  shows  wooden  bevelled 
threshold  1%  inches  thick.  Connects 
lower  ends  of  Doorframe,  forms  a  part 
of  it  and  is  let  down  into  the  floor, 
warehouses.  Accommodates  trucks. 

Fig  C.  Concrete  Floors.  Shows  lower  ends  of  Doorframe  extending  down  into  the 
floor  3  inches,  and  connected  by  angle  irons  extending  across  the  Doorway  from  one  side 
to  the  other  below  the  surface. 

Fig.  S  shows  Doorframe  with  full  standard  sill  and  head,  used  on  all  sizes  of  Door- 
frames. Suited  only  to  walking  through. 

Revolving  Ice  Cream  Doors  (Iron).     Do  not  swell  and  bind. 

Combined  Self-Closing  Ice  Door  and  Chute  of  two  styles.     Ice  Counters. 

Stevenson  Cold  Storage  Door  Co. 

CHESTER,  PENNSYLVANIA 


Installation  Diagrams. 

STOCK  SIZES. 

Stevenson's  Standard  Cold  Storage 
Doors. 


Size  of 
Doorway 

in  Clear 
2-3  x  2-0 
2-0x4-0 
2-0  x  5-0 
2-0  x  5-6 
2-0  x  6-0 
2-6  x  6-0 
3-0  x  6-0 
3-6  x  6-0 
4-0  x  6-0 
3-0  x  6-6 
3-6x6-6 
4-0  x6-6 


Size  of 

Wall  Opening 
to  receive  our 
Door  Frames 


2-6i/2 
2-3  1/2 
2-3  i/2 
2-3i/2 
2-31/2 
2-9i/2 
3-3i/2 
3-91/2 
4-31/2 
3-3 1/2 
3-9i/2 
4-3V2 


x2-  41/2 
x4-  41/2 
x5-  4V2 
x  5-10 1/2 
x6-  4V2 
x6-  4V2 
x6-  41/2 
x6-  4% 
x6-  41/2 
x  6-10 1/2 
x  6-101/2 
x  6-10 1/2 


Estimated 

Weight, 

crated 

100 

140 

170 

185 

200 

250 

300 

350 

400 

325 

380 

440 


No    feather   edge,    no   jolt,   no   splinters.      For 


CONDENSED  MILK  AND  MILK  POWDER 

-Perfect  Sterilization- 


347 


being  of  such  vital  importance  in  the  manufacture 
of  evaporated  milk,  why  be  at  the  mercy  of  skilled 
attendants  when  greater  perfection  is  possible  with 
a  "TAG"  Controller — and  at  a  considerably  less 
expense? 

With  this  "Automatic"  Control,  an  untrained  workman  can 
handle  a  number  of  sterilizers,  as  the  actual  results  are  not 
dependent  upon  him.  This  means  fewer  and  less  costly  men — 
and  no  embarrassment  to  the  quality  or  quantity  of  production 
when  a  skilled  sterilizer-man  suddenly  quits  to  serve  a  com- 
petitor. 

THE  "TAG"  COMBINATION 
Time  and  Temperature  Controller 

performs  more  perfectly  than  even  the  most  skilled  sterilizer-man 
because  no  human  hand  can  throttle  a  steam  valve  as  quickly  and 
accurately. 

It  controls  both  the  temperature  and  time  of  sterilization,  and  can 
be  adjusted  to  meet  any  variation  required — in  time  of  rise  to  the 
sterilizing  temperature — in  time  of  hold  and  the  degree  of  the  steriliza- 
tion temperature,  so  all  the  attendant  need  do  is  to  open  the  hand  steam 
valve  wide  and  the  controller  will  do  the  rest,  and  when  the  sterilizing 
period  is  over,  the  controller  will  automatically  shut  off  the  steam 
supply — blow  out  the  steam — admit  cooling  water — and  ring  a  bell. 

Write  for  further  particulars — and  also  bear  us  in  mind  when  you 
are  in  the  market  for  Indicating,  Recording  or  Controlling  Instruments, 
of  which  we  manufacture  a  style  or  type  to  exactly  meet  local  con- 
ditions. 


C.xT.TAGLIABUE  MFG.  CO. 


Brooklyn,  N.  Y.      Chicago      Boston      New  Orleans       San  Francisco 


348 


CONDENSED  MILK  AND  MILK  POWDER 


Why  the  Leading 

Condensed  Milk  Makers 
Choose  Sturges  Cans 

— because  they  are  accurate — absolutely  true  to 
measure.  Sanitary — easy  to  clean  and  keep  clean. 
Built  extra  strong  to  withstand  long  service. 


tur&es 

means 


are  built  of  the  highest  grade  of  steel 
plate,  carefully  tinned.  Seams  sol- 
dered smooth  as  a  china  bowl,  no  places 
for  milk  to  lodge  and  sour.  Write  for 
catalog  No.  111. 

STURGES  &  BURN  MFG.  CO. 

"Leaders  Since  1865" 
Chicago,  Illinois 


Torsion  Balance  Creamery  Scales 


T 

A* 


1530 

Style  No.  1530 

Factory: 

147-151  Eighth  St. 

Jersey  City,  N.  J. 


No  Knife-Edges—No  Friction — 
No  Wear 

SENSITIVE  and  ACCURATE 

Tares  and  balances  in  one  operation. 

No  loose  parts  to  shift.  Working 
parts  practically  in  one  piece. 

Torsion  Balance  four-bottle  Cream 
Test  Scale,  Style  1530,  used  by  col- 
lection stations,  creameries  and 
milk  condenseries  on  account  of  its 
extreme  accuracy. 

Your  profits  depend  on  your  tests  as 
much  as  anything  else,  probably 
more  so. 

Write  for  Catalogue. 

The  Torsion  Balance  Co. 


Pacific  Coast  Branch : 
49  California  St. 

San  Francisco,  Cal. 


Head  Office : 
92  Reade  St. 
New  York,  N.  Y. 


CONDENSED  MILK  AND  MILK  POWDER  349 

The  Vulcan  Detinning  Co.  ^ 

Sewaren,  N.  J.— Streator,  111.  ^t^?    fl^lL 

Buyers   of  — --H^V         ^^X 


Sellers   of 
VULCAN  PIG  TIN 


-r-r  '      T.TDT? AT?.Y. 

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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


